oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Evaluation of some of the Metal Levels at Different Depths from Gulf of Guinea Offshore Location
OF Joel, SB Akinde
Journal of Applied Sciences and Environmental Management , 2009,
Abstract: Study area is in the Nigeria continental shelf of the Atlantic Ocean, located within seawater depths of 20 – 25 m and geographic X and Y coordinates 337896 – 356905 and 469773 – 482786, offshore Nigeria respectively. Test was conducted to evaluate some of the metal levels at different depths from Gulf of Guinea offshore location. Samples were collected from the depth of 5m, 10m, 15m and 20m respectively and tests were conducted over a one year period on a quarterly basis. Test result indicated that mean value over the period for the metals tested was: Mg(1160mg/l), K(369mg/l), Na(8062mg/l), Ca(380mg/l), Al(<1.0mg/l), Fe(0.05mg/l), Cu(<0.05mg/l), Mn(<0.10mg/l), Zn(<0.05mg/l), Ba(<0.03mg/l), Si(<0.01mg/l), Sr(0.569mg/l), Li(0.559mg/l). This project therefore will help to provide a base-line data on the metal constituents of the Gulf of Guinea offshore location, thereby helping framework for environmental protection for offshore oil and gas activities in the Gulf of Guinea
Geochemistry of the Cretaceous-Tertiary boundary (Fish Clay) at Stevns Klint (Denmark): Ir, Ni and Zn in kerogen
PAVLE I. PREMOVIC,MILENA M. KRSMANOVIC,BRATISLAV Z. TODOROVIC,MIRJANA S. PAVLOVIC
Journal of the Serbian Chemical Society , 2006,
Abstract: Geochemical analyses of trace metals (Ir, Ni and Zn) in the kerogen of the black marl of the Cretaceous-Tertiary boundary succession (Fish Clay) at Stevns Klint (Hjerup Church) were undertaken. The data for this kerogen were in accordance with a previous hypothesis that this (insoluble) geoorganic polymer was derived from humic substances (mainly humic acids) of a nearshore soil. Substantial proportions of Ir, Ni and Zn within the kerogen structure were probably contained in these substances arriving at the sedimentary site. It is proposed that these humics were probably transported by acid surface waters (induced by the KT asteroid impact) into the shallow marine basin of Stevns Klint. It is also suggested that local leaching/weathering of the asteroidal impact fallout on the land near these waters played an important role in providing Ir, Ni and Zn for these substances. Apparently, Ir, Ni and Zn of the kerogen were created by the chondritic component of the impact ejecta fallout.
The role of sulfur in the pyrolysis of kerogen
Qin Yan,Ping’an Peng,Chiling Yu,Jinzhong Liu
Chinese Science Bulletin , 2004, DOI: 10.1007/BF02890448
Abstract: Sulfur plays an important role in the generation and evolution of hydrocarbon from organic matter. Here, a pyrolysis experiment in closed system was performed on Maoming oil shales kerogen (Type I), Maoming oil shales kerogen added with sulfur ether and Maoming oil shales kerogen added with sulphur. The results suggest that the existence of sulfur can result in: (i) higher yield of hydrocarbons generated from the kerogen; (ii) decrease of the temperature for the maximum generation of heavy hydrocarbons (the C15+ fraction) by 20°C; (iii) decrease of the temperature for the maximum generation of the aromatics fraction by 40°C, and (iv) acceleration of the aromatization process. The pyrolysates from kerogen added with sulfur are similar to the heating products of the sulfur-rich kerogen as reported in the literatures. It seems that the sulfur catalysis is also an important factor that can make the sulfur-rich kerogen generate low-mature oil at the earlier diagenesis stage, except for the weakness of the C-S and S-S bonds.
Characterization and origin types of immature and low-mature amorphous kerogen in terrestrial source rocks
Xianming Xiao,Zufa Liu,Jiagui Shen
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02898921
Abstract: The microfluorescent technique was applied to investigate the fluorescence alteration patterns of amorphous kerogen of the terrestrial source rocks of China. Two fluorescence parameters, I 546 20 andR were suggested, which can be taken to divide the amorphous kerogen into five types: algae amorphinite, biodegraded amorphinite A, B, C, and humic amorphous. On the basis of this, the Rock-Eval analysis results of source rocks were used to investigate the hydrocarbon generating potential of these amorphinite.
Characterization and origin types of immature and low-mature amorphous kerogen in terrestrial source rocks

Xianming Xiao,Zufa Liu,Jiagui Shen,

科学通报(英文版) , 1998,
Abstract: The microfluorescent technique was applied to investigate the fluorescence alteration patterns of amorphous kerogen of the terrestrial source rocks of China. Two fluorescence parameters, I 546 20 andR were suggested, which can be taken to divide the amorphous kerogen into five types: algae amorphinite, biodegraded amorphinite A, B, C, and humic amorphous. On the basis of this, the Rock-Eval analysis results of source rocks were used to investigate the hydrocarbon generating potential of these amorphinite.
Photodegradation of DOM in the Pearl River Estuary and the Beibu Gulf of the South China Sea in Autumn
秋季南海珠江口和北部湾溶解有机物的光降解

WANG Fuli,GUO Weidong,
王福利
,郭卫东

环境科学学报 , 2010,
Abstract: Fluorescence excitation emission matrix spectroscopy (EEMs) analysis combined with absorption spectroscopy measurement was used to investigate the photodegradation of four typical chromophoric dissolved organic matter (CDOM) samples from the Pearl River Estuary and the Beibu Gulf under natural solar irradiation.CDOM samples from the Pearl River Estuary and Guangxi coastal waters were more influenced by terrestrial input,while a sample from the middle of the Beibu Gulf has typical characteristics of marine CDOM,and another sample from a depth of 80 m in the south of the Beibu Gulf was somewhat influenced by the Beibu Gulf circulation.Humic-like (A,C and M) and tryptophan-like (R and T) fluorescence peaks were observed in all of the CDOM samples.Obvious photochemical degradation of their fluorescence peak intensity and absorption coefficient occurred under five day's solar irradiation in the autumn.The photodegradafion degree of samples from the Pearl River Estuary and Guangxi coastal waters was higher than samples from offshore in the Beibu Gulf,suggesting that the two former samples influenced by terrestrial input contained more chromophores.Photadegradation did not cause a significant position variation of CDOM fluorescence peaks.The fluorescence intensity of the humic-like peaks M and A,protein-like peaks R and T have the same variation trend,indicating that each pair of peaks was closely interrelated.Double peaks were found in the fluorescence peak A area,suggesting that peak A was actually a superposition of multiple fluorescence components.The spectrum slope S (270~350) of the CDOM absorption spectra increased gradually with irradiation time,which can be used to indicate the decrease of CDOM molecular weight caused by photochemical degradation.Our results show that photodegradation could play an important role in the biogeochemical cycling of biogenic elements in the South China Sea.
Whale Sharks, Rhincodon typus, Aggregate around Offshore Platforms in Qatari Waters of the Arabian Gulf to Feed on Fish Spawn  [PDF]
David P. Robinson, Mohammed Y. Jaidah, Rima W. Jabado, Katie Lee-Brooks, Nehad M. Nour El-Din, Ameena A. Al. Malki, Khaled Elmeer, Paul A. McCormick, Aaron C. Henderson, Simon J. Pierce, Rupert F. G. Ormond
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0058255
Abstract: Whale sharks, Rhincodon typus, are known to aggregate to feed in a small number of locations in tropical and subtropical waters. Here we document a newly discovered major aggregation site for whale sharks within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. Whale sharks were observed between April and September, with peak numbers observed between May and August. Density estimates of up to 100 sharks within an area of 1 km2 were recorded. Sharks ranged between four and eight metres’ estimated total length (mean 6.92±1.53 m). Most animals observed were actively feeding on surface zooplankton, consisting primarily of mackerel tuna, Euthynnus affinis, eggs.
Cretaceous – Paleogene boundary Fish Clay at H jerup (Stevns Klint, Denmark): Zn, Pb and REE in kerogen
PAVLE I. PREMOVIC,MAJA N. STANKOVIC,MIRJANA S. PAVLOVIC,MILOS G. DJORDJEVIC
Journal of the Serbian Chemical Society , 2008,
Abstract: Geochemical analyses of Zn, Pb and rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb and Lu) in the kerogen of the black marl at the Cretaceous – Paleogene boundary Fish Clay at H jerup were performed. Substantial proportions of the Zn, Pb and rare earths were probably contained in terrestrial humic substances (the kerogen precursor) arriving at the marine sedimentary site. This is in accord with a previous hypothesis that kerogen is mainly derived from humic acids of an oxic soil in of the adjacent coastal areas of eastern Denmark. It is also suggested that humics enriched in Zn, Pb and rare earth elements were transported mainly through fluvial transport into the deposition site of the Fish Clay. Local weathering/leaching of the impact–eject fallout on the land surface and local terrestrial rocks by impact-induced? acid surface waters perhaps played an important role in providing Zn, Pb and rare earths to these humic substances. Apparently, chondritic and non-chondritic Zn originated from the impact fallout; Pb and rare earth elements were most likely sourced by exposed rocks in the coastal areas of eastern Denmark.
The kerogen vanadyl porphyrins: incorporation during catagenesis
PAVLE I. PREMOVIC,IVANA R. TONSA,DRAGAN M. DJORDJEVIC,MIROSLAV P. PREMOVIC
Journal of the Serbian Chemical Society , 1999,
Abstract: Natural vanadyl (VO2+)-deoxophylloerythroetioporphyrins (DPEP) have been shown to be capable of reacting and quantitatively incorporating into immature kerogen model materials (torbanite, lignites, subbituminous coal and immature lacustrine kerogen) at 200°C for 72 h in the absence/presence of air. Electron spin resonance was used to monitor the incorporation of VO2+-DPEP into the kerogen models. The products of the incorporation resemble natural kerogen enriched with VO2+. The simulation experiments described in this paper clearly show that the kerogen VO2+-P may originate from VO2+-DPEP incorporation into the kerogen macromolecular structures during catagenesis.
Influence of humic substances on results of the spectrophotometric (TPTZ) analysis of monosaccharides  [cached]
Waldemar Grzybowski,Magdalena Dudzi?ska
Oceanologia , 2004,
Abstract: A spectrophotometric method of monosaccharide analysis was assessed with regard to its non-selectivity towards humic substances. Analysis of model solutions showed that it responds positively to both marine and terrestrial humics. The systematic error in monosaccharide analysis (in glucose equivalents) was 0.18-0.20 mg per 1 mg of Aldrich humic acid and 0.11-0.12 mg per 1 mg of humic substances isolated from Gulf of Gdańsk water.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.