Search results for "ISOTOPE"

Penning-trap mass measurements on 92, 94-98, 100Mo with JYFLTRAP

2012

Penning-trap measurements on stable 92, 94-98, 100Mo isotopes have been performed with relative accuracy of \ensuremath1⋅10−8\ensuremath1⋅10−8 with the JYFLTRAP Penning-trap mass spectrometer by using 85Rb as a reference. The Mo isotopes have been found to be about 3keV more bound than given in the Atomic Mass Evaluation 2003 (AME03). The results confirm that the discrepancy between the ISOLTRAP and JYFLTRAP data for 101-105Cd isotopes was due to an erroneous value in the AME03 for 96Mo used as a reference at JYFLTRAP. The measured frequency ratios of Mo isotopes have been used to update mass-excess values of 30 neutron-deficient nuclides measured at JYFLTRAP. peerReviewed

Diet composition and seasonal feeding patterns of a freshwater ringed seal (Pusa hispida saimensis)

2015

The Saimaa ringed seal (Pusa hispida saimensis) is one of the few freshwater seal populations worldwide. The major conservation issue of this critically endangered population is bycatch mortality. We used digestive tract content and stable isotopes (d13C and d15N) to estimate the diet and seasonal feeding patterns for gaining better understanding of the seals feeding habits and potential conservation implications. The diet was similar across age groups. Altogether 15 fish species were identified and the most important were smelt (Osmerus eperlanus), ruff (Gymnocephalus cernuus), perch (Perca fluviatilis), vendace (Coregonus albula) and cyprinids. The high d15N values suggested that the seal…

A stable isotope study of the hydrological and carbon cycle in meromictic lake, Lovojärvi

2012

Lake Lovojärvi, at its deepest point of 17.5 m, is permanently stratified forming two water layers. The mixolimnion (the upper layer, from 0 to 10 m depth) is affected by seasonal changes while the monimolimnion (bottom layer, from 10 to 17.5 m depth) does not mix and is not affected by seasonal changes. As a result, the lake stores large quantities of dissolved inorganic carbon and methane. I used a multiple stable isotope approach to gain insight into the carbon cycle and water balance of Lovojärvi. The δ18O and δ2H profiles reveal that at the 7 m depth in the mixolimnion, there is a sub-surface stream whose isotopic characteristics are similar to surface streams from a nearby mire, sugge…

Ontogenetic δ15N Trends and Multidecadal Variability in Shells of the Bivalve Mollusk, Arctica islandica

2021

Bulk stable nitrogen isotope values of the carbonate-bound organic matrix in bivalve shells (δ15NCBOM) are increasingly used to assess past food web dynamics, track anthropogenic nitrogen pollution and reconstruct hydrographic changes. However, it remains unresolved if the δ15NCBOM values are also affected by directed ontogenetic trends which can bias ecological and environmental interpretations. This very aspect is tested here with modern and fossil specimens of the long-lived ocean quahog, Arctica islandica, collected from different sites and water depths in the NE Atlantic Ocean. As demonstrated, δ15NCBOM values from the long chronologies show a general decrease through lifetime by −0.00…

Responses of zooplankton to cane sugar additions to a small humic lake, Alinen Mustajärvi

2010

The response to projected increase in dissolved organic carbon (DOC) loading to boreal lakes is being studied in lake Alinen Mustajärvi, a small humic lake in southern Finland, where labile DOC concentration has been artificially increased during 2008 and 2009 by monthly additions of cane sugar. As part of this wider project, in this thesis the responses of the zooplankton community to cane sugar addition were studied. Zooplankton samples were collected monthly in the ice-free periods of 2007, 2008 and 2009 and the mean densities and mean carbon biomasses of rotifers and crustacean zooplankton (cladocerans and copepods) were calculated. Stable isotope analyses (δ13C and δ15N) were made for …

Paleoclimatic changes in the Serravallian record of the Mediterranean area

2004

High-resolution laser spectroscopy of long-lived plutonium isotopes

2017

Long-lived isotopes of plutonium were studied using two complementary techniques, high-resolution resonance ionisation spectroscopy (HR-RIS) and collinear laser spectroscopy (CLS). Isotope shifts have been measured on the $5f^67s^2\ ^7F_0 \rightarrow 5f^56d^27s\ (J=1)$ and $5f^67s^2\ ^7F_1 \rightarrow 5f^67s7p\ (J=2)$ atomic transitions using the HR-RIS method and the hyperfine factors have been extracted for the odd mass nuclei $^{239,241}$Pu. Collinear laser spectroscopy was performed on the $5f^67s\ ^8F_{1/2} \rightarrow J=1/2\; (27523.61\text{cm}^{-1})$ ionic transition with the hyperfine $A$ factors measured for $^{239}$Pu. Changes in mean-squared charge radii have been extracted and s…

Huit objets de cuivre et de bronze du piémont pyrénéen oriental : analyse croisée typologique et métallique

2015

Cet article porte sur huit pièces à base de cuivre – deux haches plates et six poignards – provenant de la zone sous-pyrénéenne orientale (Corbières, Haute Vallée de l’Aude, Pays d’OImes), dans les départements de l’Aude et de l’Ariège de l’Est (région de Lavelanet). Elles sont décrites et replacées dans leur contexte typochronologique, alors que les aspects technoéconomiques sont envisagés via la composition métallique (composition élémentaire et rapports isotopiques du plomb). Cinq objets en cuivre – deux haches et trois poignards – sont attribués au Chalcolithique. L’une des haches se rapproche des types nord-ibériques et son importation depuis cette région est suggérée par les analyses …

The origin of heavy metals and radionuclides accumulated in the soil and biota samples collected in Svalbard, near Longyearbyen

2017

Heavy metals and radioactive compounds are potentially hazardous substances for plants, animals and humans in the Arctic. A good knowledge of the spatial variation of these substances in soil and primary producers, and their sources, is therefore essential. In the samples of lichen Thamnolia vermicularis, Salix polaris and Cassiope tetragona, and the soil samples collected in 2014 in Svalbard near Longyearbyen, the concentrations of the following heavy metals were determined: Mn, Ni, Cu, Zn, Cd, Pb and Hg, as well as the activity concentrations of the following: K-40, Cs-137, Pb-210, Pb-212, Bi-212, Bi-214, Pb-214, Ac-228, Th-231 and U-235 in the soil samples. The differences in the concent…

Preliminary results of studies on radioisotopes activity concentrations in vicinity of cement works

2012

W wielu miejscowościach znajdują się pozostałości po zakładach przemysłowych. Nawet jeśli taki teren został zrekultywowany, często obszary położone nieco dalej nie zostały przywrócone do pierwotnego stanu. Na takich terenach można spodziewać się istnienia podwyższonych stężeń różnych pierwiastków, w tym izotopów promieniotwórczych. Do badań pobrano próbki gleby na obszarze byłej cementowni „Piast”, znajdującej się w granicach miasta Opola oraz na obszarze pobliskich ogródków działkowych. W badanych próbkach stwierdzono obecność naturalnych izotopów promieniotwórczych oraz 137Cs. Największe aktywności wykazywały 40K oraz 137Cs. Aktywności naturalnych izotopów promieniotwórczych były znacznie…