نتایج جستجو برای: geochemical

تعداد نتایج: 12072  

1992
FORREST M. HOFFMAN VIJAY S. TRIPATHI

-This paper presents the design and development of a Geochemical Expert System prototype (GES) for analyzing solution-mineral interactions in nature. The emphasis is placed on expert system design and knowledge representation. One of the most challenging and research-intensive steps was the identification of the key geochemical characteristics that would enable the expert system to identify sal...

2006
PHILIP J. BINNING MICHAEL A. CELIA LI LI

Multicomponent contaminant transport models in groundwater are typically based on assumptions of local geochemical equilibrium on the grid scale. In heterogenous systems there may be significant coupling between transport processes and geochemical equilibrium at smaller than grid block scale. When these processes are upscaled to grid scale, geochemical evolution may take on a kinetic character....

2008
Jeffrey M Dick

Background: Proteins of various compositions are required by organisms inhabiting different environments. The energetic demands for protein formation are a function of the compositions of proteins as well as geochemical variables including temperature, pressure, oxygen fugacity and pH. The purpose of this study was to explore the dependence of metastable equilibrium states of protein systems on...

2010
Pranab Das Sridhar D Iyer

The geochemical discriminate diagrams help to distinguish the volcanics recovered from different tectonic settings but these diagrams tend to group the ocean floor basalts (OFB) under one class i.e., as mid-oceanic ridge basalts (MORB). Hence, a method is specifically needed to identify the OFB as normal (N-MORB), enriched (E-MORB) and ocean island basalts (OIB). We have applied Artificial Neur...

2016
Jaana Jarva Timo Tarvainen Reijo Salminen

This study provides an overview on the development of the guidelines and legislation related to soil contamination in Finland, with the main focus on geochemical baselines. The use of geochemical baseline surveys in the assessment soil contamination in Finland and in some other countries is briefly discussed and the current practices in Finland are presented. Finally, the geochemical baselines ...

2011
Isla S. Castañeda Stefan Schouten

Molecular organic geochemical proxies are increasingly being utilized to reconstruct past environmental conditions as new tools continue to be discovered and developed. To date, organic geochemical proxies have been developed mainly for use in marine systems and are widely used in paleoceanography. In contrast, organic proxies have been less commonly used on lacustrine sedimentary records. One ...

Journal: :Journal of contaminant hydrology 2001
N Sun M Elimelech N Z Sun J N Ryan

A two-dimensional model for colloid transport in geochemically and physically heterogeneous porous media is presented. The model considers patchwise geochemical heterogeneity, which is suitable to describe the chemical variability of many surficial aquifers with ferric oxyhydroxide-coated porous matrix, as well as spatial variability of hydraulic conductivity, which results in heterogeneous flo...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2012
Steffen Leth Jorgensen Bjarte Hannisdal Anders Lanzén Tamara Baumberger Kristin Flesland Rita Fonseca Lise Ovreås Ida H Steen Ingunn H Thorseth Rolf B Pedersen Christa Schleper

Microbial communities and their associated metabolic activity in marine sediments have a profound impact on global biogeochemical cycles. Their composition and structure are attributed to geochemical and physical factors, but finding direct correlations has remained a challenge. Here we show a significant statistical relationship between variation in geochemical composition and prokaryotic comm...

Journal: :journal of mining and environment 2015
h. shahi r. ghavami riabi a. kamkar ruhani h. asadi haroni

in this research work, the frequency domain (fd) of surface geochemical data was analyzed to decompose the complex geochemical patterns related to different depths of the mineral deposit. in order to predict the variation in mineralization in the depth and identify the deep geochemical anomalies and blind mineralization using the surface geochemical data for the dalli cu-au porphyry deposit, a ...

Abstract Most conventional statistical methods aiming at defining geochemical concentration thresholds for separating anomalies from background have limited effectiveness in areas with complex geological settings and variable lithology. In this paper, median+2MAD as a method of exploratory data analysis (EDA) and concentration-area (C-A) fractal model as two effective approaches in separation g...

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