Search Results

You are looking at 1 - 9 of 9 items for :

  • "Natural sediment" x
  • Chemistry and Chemical Engineering x
  • All content x
Clear All

Abstract  

Release of long-lived radioactivity to the aquatic bodies from various nuclear fuel cycle related operations is of great environmental concern in view of their possible migration into biosphere. This migration is significantly influenced by various factors such as pH, complexing ions present in aquatic environment and sorption of species involving radionuclides on the sediments around the water bodies. 241/243Am are two major radionuclides which can contribute a great deal to radioactivity for several thousand years. In the present study, 241Am sorption on natural sediment collected from site near a nuclear installation in India, has been investigated under the varying conditions of pH (3–10) and ionic strength [I = 0.01–1 M (NaClO4)]. The sorption of Am increased with pH of the aqueous medium [10% (pH 2) to ~100% (pH 10)], which was explained in terms of the increased negative surface charge on the sediment particles. There was marginal variation in Am(III) sorption with increased ionic strength (within error limits) of the aqueous medium suggesting inner-sphere complexation/sorption process. Sediment was characterized for its elemental composition and structural phases using Energy Dispersive X-Ray (SEM-EDX) and X-Ray Diffraction (XRD) techniques. Zeta-potential measurement at I = 0.1 M (NaClO4) suggested that Point of Zero Charge (pHPZC) was ~2, indicating the presence of silica as major component in the sediment. Kurabtov plot using sorption data as a function of pH at fixed I = 0.1 M (NaClO4) indicated the presence of multiple Am(III) species present on the surface. Potentiometric titration of the suspension indicated the presence of mineral oxide like behavior and assuming a generic nature (≡XOH) for all types of surface sites, protonation–deprotonation constants and total number of sites have been obtained. The sorption data has been modeled using 2-pK Diffuse Double Layer Surface Complexation Model (DDL-SCM). ≡XOAm2+ has been identified as the main species responsible for the sorption profile.

Restricted access

Abstract  

Chemical and physical properties of Suez Canal bottom sediments (SCBS) and sea water at port Tawfeek area, the south entrance of Suez canal, have been studied. The SCBS was separated into its size fractions (natural sediment, sand, silt and clay). These different sediment fractions were allwed to be in equilibrium with89Sr,60Co and134Cs solutions. Desorption studies were carried out on these contaminated sediments.

Restricted access

Abstract  

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, 40K) and antropogenic (Pu, 241Am, 137Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. 137Cs and 40K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.

Restricted access

Abstract  

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, 40K) and antropogenic (Pu, 241Am, 137Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. 137Cs and 40K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.

Restricted access

Abstract  

The knowledge of radioactive and stable elements partitioning to natural sediment systems is essential for modelling their environmental fate. A sequential extraction method consisting of six operationally-defined fractions has been developed for determining the geochemical partitioning of natural (U, Th, 40K) and antropogenic (Pu, 241Am, 137Cs) radionuclides in a 10 cm deep sediment sample collected in the Tyrrhenian sea (Gaeta Gulf, Italy) in front of the Garigliano Nuclear Power Plant. 137Cs and 40K were measured by gamma-spectrometry. Extraction chromatography with Microthene-TOPO (U, Th), Microthene-TNOA (Pu) and Microthene-HDEHP (Am) was used for the chemical separation of the alpha-emitters: after electrodeposition alpha-spectrometry was carried out. Some stable elements (Fe, Mn, Al, Ca, Pb, Ba, Ti, Sr, Cu, Ni) were also determined in the different fractions to get more information about the chemical association of the radionuclides.

Restricted access

A középső bronzkori (ca. 2000/1900—1500/1450 cal BC) Vatya-kultúra erődített, több rétegű tell-településekből, változó méretű és jellegű nyíltszíni telepekből álló településhálózatainak talajtani és földtani képződményei egyaránt értékes elemei kulturális és természeti örökségünknek. Az ún. „földvár“ talajtani és környezettörténeti jelentősége abban áll, hogy eltemetett talajokat, illetve az emberi megtelepedés eredményeképpen létrejött és módosult antropogén üledékrétegeket rejtenek. Ezek vizsgálata környezettörténeti, illetve az emberi környezetalakítással kapcsolatos következtetéseknek nyitnak teret.

Kakucs—Turján mögött“ lelőhely a Kiskunsági-homokhát, a Pesti hordalékkúp-síkság, illetve a Pilis—Alpári-homokhát találkozásánál fekszik, közvetlenül az ócsai Turjánvidék szomszédságában. A térképező talajtani fúrás eszközének alkalmazásával lehetőségünk nyílt arra, hogy feltérképezzük a bronzkori település talajtani, illetve sekélyföldtani viszonyait. Ennek érdekében egy olyan nagyfelbontású és célzott fúrási tervet dolgoztunk ki, amely amellett, hogy alkalmas a terület részletes és pontos talajtani, üledéktani és rétegtani viszonyainak feltérképezésére, segíti a régészeti lelőhely fejlődéstörténetének, illetve tafonómiájának megértését is.

A nagyfelbontású térképező fúrással, helyszíni talajvizsgálati módszerekkel, valamint alapvető laboratóriumi mérések elvégzésével meghatároztuk és leírtuk a lelőhelynek a fedő talajképződmény alatti antropogén hatásra kifejlődött és módosult talajainak, valamint üledékeinek vertikális és horizontális kiterjedését. Ennek keretében vizsgáltuk a hármas tagolású lelőhely kerítőárkainak betöltését. Eredményeink arra utalnak, hogy a közel 4–4,5 méteres mélységű egykori árkok a korabeli felszíni talajtakaróra jellemző nagyobb humusz és szerves anyag tartalmú rétegekkel töltődtek fel. Emellett, olyan — a fokozatos betöltődés morfológiai jegyeiként meghatározott — (mikro)rétegeket is sikerült felismerni a bolygatatlan fúrómagokban, amelyek a vízzel időszakosan feltöltődött árkokban rakódhattak le.

A nagyfelbontású térképező fúrással végzett felmérés alapján sikerült megrajzolni egy homok textúrájú talajtani környezetben elhelyezkedő és ebben fejlődő, majd pusztuló lelőhely rétegtani viszonyait, illetve lehetséges fejlődéstörténetét.

Restricted access

. Bertraux , J , Frohlich , F , Ildefonse , P . Multicomponent analysis of FTIR spectra: quantification of amorphous and crystallized mineral phases in synthetic and natural sediments . J Sediment Res . 1998 ; 68 : 440 – 447

Restricted access
Agrokémia és Talajtan
Authors: András Makó, Tamás Varga, Hilda Hernádi, Viktória Labancz, and Gyöngyi Barna

for use with natural sediments. Research Methods Papers. 561 – 564 . McKeague , J. A. 1978 . Manual on soil sampling and

Restricted access

McCave, I. N. et al., 1986. Evaluation of a laser-diffraction-size analyser for use with natural sediments. J. Sedimentol. Petrol. 56 . 561–564. McCave I. N. Evaluation of a laser

Restricted access