The influence of oxidizing and reducing conditions upon the distribution of some elements in lake sediments (original) (raw)
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.
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 ( .
Depth concentration profiles of 26 elements, i.e. trace elements (As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb, Rb, Sr, V and Zn), lithophiles (Si, Al, Fe, Mn, Na, K, Mg, Ca and Ti) and nutrients (C, P, N, S) have been established in a sediment core collected at the Respomuso Lake (Pyrenees, Spain). This high altitude lake of glacier origin was transformed into reservoir in the fifties of last century. Correlations among the depth profiles of the above elements were established. HCl-extractable elements, which are better related to bioavailability, followed the profiles of total contents. Principal component analysis was applied to establish the binding behaviour of trace elements in the sediment matrix and, in turn, to search for their anthropogenic or natural sources. It was seen that Cu, Ni, Pb, Sr and Zn clustered together, and with exception of Sr, they were not clearly associated with any major component of the sediment. Their depth profiles correlate well with each other, hence indicating their presence as a result of atmospheric pollution. Redox-sensitive elements such as Fe and Mn follow a similar trend along the vertical profile. Depth profiles of As an Co correlate well with those of Fe and Mn. Principal component analysis showed that As, Co, Fe and Mn clustered together, which confirms the close association of As and Co with Fe-Mn oxyhydroxides. As concentrations in many strata exceed the ERM value, and therefore, significant biological effects are expected. Dissolution of minerals such as pyrite, chalcopyrite and galena taking part in the mineralogy of this area accounts for the As concentration found. Ba, Cr, Rb and V were associated with the sediment matrix (aluminosilicates), hence showing low mobility.
Geochemical Atlas of Finland: preliminary aspects
Journal of Geochemical Exploration, 1989
The primary data for the Atlas are based on 1057 composite till samples collected from all over Finland, at a mean sampling density of one sample per 300 km 2. Each composite sample consists of five subsamples, which were collected from an area of 0.5 by 2.5 km e (elongated perpendicular to the direction of ice movement). The majority of samples were taken with a light percussion drill at an averge depth of 1.5 m.
Geochemistry: Exploration, Environment, Analysis
Forest rings are large circular features common in boreal forests in Ontario, Canada, characterized by ring-shaped topographic depressions in carbonate-rich soil. This paper documents the compositional variation of soil and of the peat that commonly fills the depression, along transects across two representative rings: one centred on an accumulation of CH4 in glacial sediments and the other on H2S in both glacial sediments and bedrock. Clayey mineral soil at the ring edge (annulus) shows low pH, oxidation-reduction potential (ORP), Ca and carbonate, and high Al, Fe and Mn by both aqua regia digestion and a 0.25M hydroxylamine hydrochloride leach (0.25M NH2OH.HCl at 60°C). Antithetic responses occur in the overlying peat, including elevated carbonate and pH over the areas with low pH, ORP and carbonate in the mineral soil. The observed relationships suggest vertical migration of carbonate species from mineral soil into peat at the annulus, and lateral migration from the annulus to adjacent areas in the mineral soil. The geochemical data support the hypothesis that forest rings are the surface expression of reduced chimneys, similar to those observed over metallic mineral deposits, despite both these sites being known to be barren. Strongly negative ORP values in shallow soils in the annulus suggest autotrophic microbiological activity contributes to the sharp change in redox conditions at the ring boundaries. The similar geochemical responses at for-est rings and soils over mineral deposits show that these features can be used to understand the variation in redox, pH, metals and soil hydrocarbons over mineral deposits and to help differentiate ore-related from secondary geochemical features due to the presence of a reduced chimney.