The influence of oxidizing and reducing conditions upon the distribution of some elements in lake sediments (original) (raw)
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International Journal of Earth Sciences, 2012
The terrestrial surface, the ''skin of the earth'', is an important interface for global (geochemical) material fluxes between major reservoirs of the Earth system: continental and oceanic crust, ocean and atmosphere. Because of a lack in knowledge of the geochemical composition of the terrestrial surface, it is not well understood how the geochemical evolution of the Earth's crust is impacted by its properties. Therefore, here a first estimate of the geochemical composition of the terrestrial surface is provided, which can be used for further analysis. The geochemical average compositions of distinct lithological classes are calculated based on a literature review and applied to a global lithological map. Comparison with the bulk composition of the upper continental crust shows that the geochemical composition of the terrestrial surface (below the soil horizons) is significantly different from the assumed average of the upper continental crust. Specifically, the elements Ca, S, C, Cl and Mg are enriched at the terrestrial surface, while Na is depleted (and probably K). Analysis of these results provide further evidence that chemical weathering, chemical alteration of minerals in marine settings, biogeochemical processes (e.g. sulphate reduction in sediments and biomineralization) and evaporite deposition are important for the geochemical composition of the terrestrial surface on geological time scales. The movement of significant amounts of carbonate to the terrestrial surface is identified as the major process for observed Ca-differences. Because abrupt and significant changes of the carbonate abundance on the terrestrial surface are likely influencing CO 2-consumption rates by chemical weathering on geological time scales and thus the carbon cycle, refined, spatially resolved analysis is suggested. This should include the recognition of the geochemical composition of the shelf areas, now being below sea level.
Geochemical characterization of subsurface sediments
Proefschrift ter verkrijging van de graad van doctor in de landbouw-en milieuwetenschappen, op gezag van de rector magnificus, Dr. C.M. Karssen, in het openbaar te verdedigen op woensdag 25 maart 1998 des namiddags te half twee in de Aula van de Landbouwuniversiteit te Wageningen Vx Cx r 'ï ( .
Mineralogy, petrography and geochemistry of sediments used in pollutant sorption experiments
2003
Sediments from the bottom of the Horní Bečva Reservoir (HBS 2, HBS 6, HBV 4) contain identical mineral phases and vary in clay contents (HBS 2-1 wt%, HBV 4-18.5 wt%). With the increasing clay amount, the contents of Fe-oxyhydroxides and organic matter also increase. Clay minerals in lake bottom sediments are represented mainly by kaolinite (K), chlorite (C) and mixed-layer illite/smectite (I/S) with expandability of ca. 40 % S [(K > C) = I/S]. Neogene argillaceous and silty sandstone from Staré Město (SMA) comprises the highest amount of clay fraction (31 wt%). Phyllosilicates, especially smectite and kaolinite (S = K), surround the rock-forming minerals. H (Hevlín) and Žd (Ždánice) Paleogene and Neogene silty sandstones contain carbonate cement (dolomite > calcite). The dominant clay mineral in both sandstones is I/S with expandability of ca. 95 % S. The H sample contains also a considerable amount of chlorite and discrete illite (S > C > Id). Žd sample comprises less kaolinite plus chlorite and discrete illite [S > (K > C) > Id]. The soil horizon from Lelekovice (Le 4) is typical in the presence of carbonates, weathered amphiboles and epidote minerals (derived from a metabasite source), in higher contents of clay fraction (15 wt%), organic matter and Fe-oxyhydroxides. The main clay mineral in sample Le 4 is mixed-layer illite/smectite with expandability around 65 % S and kaolinite (I/S > K). The soil horizon from Červenohorské sedlo Saddle (SČS 5) is typical in the absence of feldspars, in the high content of muscovite and biotite (derived from mica schists) and in the highest amount of organic matter and Fe-oxyhydroxides. Clay minerals of this sample include mostly discrete illite; chlorite and kaolinite are less abundant (Id > C > K).
Environment and Geochemistry of Sediments
Editorial Office MDPI St. Alban-Anlage 66 4052 Basel, Switzerland, 2023
This reprint considers a vast range of questions devoted to environmental geochemistry. The Special Issue “Environment and Geochemistry of Sediments” includes 10 papers. The themes of research cover different problems of the geochemistry of sediments, such as the reconstruction of the paleoenvironment in the lake basins in the high latitude zones on the base of geochemical indicators, the processes of the sedimentary environment and climate evolution during the Late Carboniferous–Early Permian period in the central Junggar Basin (China), and the study of the paleoenvironment and bio-sequence stratigraphy in the Cretaceous pelagic carbonate succession part of the eastern Tethys. Several articles discuss the features of the geochemistry of sedimentation in places of prehistoric anthropogenic activity, for example, based on lithological and geochronological analyses, magnetic susceptibility, and microcharcoal studies, the anthropogenic sources of metals in south-eastern Baltic lake sediments from the Neolithic to the Medieval Age were determined. A new approach using the geochemical indication was developed for the determination of the functional zones of prehistoric archaeological sites in Eastern Europe. The application of geochemical multi-element and geochronological analyses of the Iron Age and early Roman cultural layers was considered at the archaeological site in the Netherlands. Some papers explore to the pollution hazard problem concerning for example the accumulation and distribution of a hazardous contaminant, mercury (Hg), in the basin of Onega Lake, Russia, the second largest lake in Europe, and the distribution of arsenic in the soils of the Verkhnekamskoe potassium salt deposit, Perm Krai, Russia. The ecological state of basins as a result of technogenic processes using a geochemical approach is illuminated in the papers devoted to the mineralogical and geochemical contents of the bottom sediments of Al-Kharrar and Al-Shuaiba Lagoons, Red Sea, Saudi Arabia. The Guest Editors of this Special Issue would like to thank all of the authors for their valuable contributions.
Inorganic data from El'gygytgyn Lake sediments: stages 6–11
Climate of the Past Discussions, 2013
Geochemical study was performed on sediment of deep drilling core from El'gygytgyn Lake, located in central Chukotka, northeastern Russia (67 • 30 N; 172 • 05 E). Major and rare elements were determined by X-ray fluorescence spectroscopy (XRF) on 600 samples covering the timeframe between ca. 450 and 125 ka corresponding to Marine Isotope Stages (MIS) 11 to 6. Inorganic geochemistry data indicates significant variations in the elemental compositions corresponding to the glacials and interglacials periods. Interglacial sediments are characterized by high contents of SiO 2 , Na 2 O, CaO, K 2 O, Sr and are depleted in Al 2 O 3 , Fe 2 O 3 , TiO 2 , MgO. Extreme enrichments in SiO 2 during MIS 11.3 and 9.3 are caused by an enhanced flux of biogenic silica (BSi). Geochemical structure of stage 11 shows very similar peculiarities to features of stage 11 from records of Lake Baikal/SE Siberia and Antarctic ice cores. High contents of TiO 2 , Fe 2 O 3 , MgO, Al 2 O 3 , LOI, Ni, Cr and Zr are typical for sediments of glacial stages, among those MIS 7.4 and 6.6 are the most marked. Peaks in the Fe 2 O 3 content and coinciding low Fe 2 O 3 /MnO ratios during glacials indicate reducing condition in the sediments. This is also supported by enrichments in P 2 O 5 and MnO, indicating an increased abundance of authigenic fine grained vivianite. Some elemental ratios indicate an enhanced alteration of glacial sediments accompanied by a loss of mobile elements, like Na, Ca, K and Sr. The higher alteration of sediments can presumably be traced back to changes in the sedimentation regime and diagenetic processes, and thus, reflects environmental changes.
Estuarine, Coastal and Shelf Science, 2002
A study of an anoxic sediment core from Authie Bay in northern France has been undertaken; porewaters and sedimentary solid phases have been analysed by several techniques (inductively coupled plasma atomic emission spectroscopy; graphite-furnace atomic absorption spectroscopy; X-ray diffraction; and electron spin resonance spectroscopy). The chemical speciation versus depth of the major elements (Ca, Fe, Mg, Mn, P and Sr), some trace elements (Cd and Zn) and especially sulfur [i.e., dissolved sulfur as Acid Volatile Sulfide (AVS) and Chromium Reducible Sulfur (CRS)] have also been performed using sequential extraction procedures. Together with these analytical data, thermodynamic calculations have been used in order to gain information about the effects of microbial degradation of organic matter in these recent sediments on these elements during early diagenesis and/or the possible generation of new characteristic assemblages of authigenic mineral precipitates of carbonates, phosphates and/or sulfides. Thus, these calculations have shown that iron sulfide precipitates in interstitial waters to give the crystalline form greigite and, to a lesser extent, mackinawite, whereas different divalent metals (noted Me) as Mg, Mn, Sr, Cd, Zn and even Fe interact favourably with Ca 2+ and CO 2 3 [through a removal of these elements from anoxic porewaters by (co)precipitation and/or adsorption on to the sedimentary carbonate phase (calcite)] to give (1) a solid mineral: dolomite [CaMg(CO 3 ) 2 ]; and (2) solid solutions as Me x Ca 1 x CO 3 . The distribution coefficients for these metals in calcite have been calculated and compared to those reported in the literature.
Geochemistry of Background Sediment Samples at Technical Area 39, Los Alamos National Laboratory
1998
An AfFrnzafive Acfion/Eqtml Opporfziizity Employer This report was prepared as an accoiiiit of work sponsored by an agency cfthe United States Goveninient. Neither Tlie Regents of tlie University of California, the United States Goveninient nor any agency tlrereoj nor any of flreir eniployees, makes any 7uarranty, express or iniplied, or assiinies any legal liability or responsibilityfor the accuracy, conipleteness, or iisefnbiess ofany ii2fornration, apparatus, product, or process disclosed, or represents flint its iise woiild not infringe privafely owned rights. Reference lierein to any speapc conmiercial product, process, or satice by trade name, trademark, inaniifiactiirer, or othenuise, does not necessarily constitute or iniply its endorsenisit, reconimeiidafioiz, or favmhg by The Regents offlie Uiiiversify ofcalifonzia, the Uiiifed Sfafes Goveriznieizf, or arzy ngmi~lj thereof. The views arid opinions of aiifliors expressed herein do iiof wecessnrily sfafe or rflecf fliose of The Regents of the Universify of California, flre United Sfafes Govenznrenf, or anyagericlj fliereof. Los Alanios National Laboratory strongly supports academic freedom and a researclier's right to piiblisli; ns an institiition, lrowever, tlie Laboratory does not endorse the viewpoint of a piiblication or guarantee its teclriiical correctness. i DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. LA-13535-MS Geochemist y of Background Sediment Samples
2014
I am especially thankful to MY MOTHER for all the help, care, encouraging and faith in my success. SUMMARY iii The Fifth Triglav Lake is a remote mountain lake in the Julian Alps. The area of the Julian Alps where the lake is situated is protected by law and lies within the Triglav National Park (TNP). The distribution of different forms of phosphorus, the composition of organic matter (organic carbon and total nitrogen concentrations), as well as stable carbon isotopic composition were determined in the surface sediments of the Fifth Triglav Lake, in order to study the impact of anthropogenic activity on the lake and natural lake characteristics. C/N ratios and stable isotopes in the surface sediments were employed to assess sources of organic matter in the sediments. Surface sediment atomic C/N ratios ranged from 13.3 to 15.6, suggesting that both autochthonous and allochthonous sources contribute organic matter to this lake constituting approximately 49-63 % and 37-51 %, respectively of the total organic matter. δ 13 C values varied from-22.4 to-26.4 ‰ which could also indicate contribution of both autochthonous and allochthonous sources. Total phosphorus concentrations ranged from 802 to 1704 µg/g dry weight sediment. Most of phosphorus compounds are in organic form, followed by calcium-bound, iron-bound, aluminum-bound and loosely bound phosphorus compounds. Phosphorus compounds are unevenly distributed across the lake. Correlations among all geochemical parameters were also calculated. Finally, multi-attribute decision model was developed with DEXi software. In order to understand the dimension of the ecological effects on the lake, four main parameters were chosen, i.e. the trophic state, lake characteristics, environmental parameters and anthropogenic stressors. Dependence of environmental impact on various external factors beyond our control, such as temperature, precipitation, retention time, and factors on which we have influence, such as the amount of wastewater and the presence of fish in the lake was also evaluated. According to the model results, fish seem to be the most important factor affecting the state of the lake.