Stable Isotope

This paper deals with natural abundance of 15N and 13C in the soil and needles of the pine forest (Pinus roxburghii, Sargent) along an altitudinal gradient. The study area lies in the elevation range of 1,200 m to 2,200 m in Kathmanduvalley of Nepal. The higher altitude soil was found to be much more depleted of 13C than the lower altitude soil. The decreasing trend of C-isotope (as well as the trend of N-isotope) might be attributed to the lower mineralisation rate and net nitrification rate at the higher altitude. The observed differences in isotopic N- and C-contents of needles and soils across altitudinal gradients in this study are a result of the combination of environmentally induced variations in physiological and morphological differences. For example, altitudinal variation in needle δ15N and δ13C at the research site indicates that the needle isotopic composition is related to nitrogen availability at a site.

In the eastern part of the Western Srednogorie Unit, a specific succession of Gintsi and Glozhene–Slivnitsa formations has provided micropalaeontological evidence of late Tithonian (Chitinoidella and Praetintinnopsella zones) and mid-Berriasian (Elliptica Subzone of the Calpionella Zone) age on the basis of 38 chitinoidellid and calpionellid species. A significant stratigraphic hiatus has been documented within the Glozhene–Slivnitsa Formation since the Crassicollaria Zone, as well as the Alpina+Remaniella subzones of Calpionella Zone, are absent from the section. The conformably overlaying Salash Formation is of mid-Berriasian age (Elliptica Subzone) and is locally characterized by presence of calcareous sandstones. Seven carbonate microfacies have been determined, which suggest that the carbonates were deposited in carbonate ramp rather than under pelagic conditions. Indeed, the upper part of the sections studied has revealed an upward-deepening trend.

Petrography, Eh‐pH calculations and the stable isotope composition of oxygen are used to interpret geochemical processes that occurred during iron oxide mineralization and dolomitization along the Menuha Ridge segment of the Paran Fault, southern Israel, adjacent to the Dead Sea Transform (DST). Iron mineralization is strongly localized in the fault zone as ferruginous lenses, whereas Fe dolomitization spreads laterally into the Cenomanian‐Turonian carbonate host rock as stratabound beds. The average oxygen isotope fractionation between syngenetic quartz and iron oxides in the ferruginous lenses gives a temperature of 50 ± 10°C and δ18O SMOW water = −3.5‰; consistent with an origin from metalliferous groundwater flow in the sedimentary basin. Ferroan dolomite initially formed under strongly reducing conditions, but this was followed by oxidation and pseudomorphic replacement of the dolomite by a mesh of fine‐grained iron oxides (simple zoned dolomites). This cycle of ferroan dolomit...

Stable isotope analysis has emerged as an important tool in aquatic ecology. For fish, dorsal muscle from sacrificed individuals has traditionally been used in stable isotope studies; however, there are many instances when lethal sampling is undesirable. We evaluated the feasibility of using adipose and caudal fin clips as alternatives to muscle in stable isotope studies for five species of salmonids. Because fish size and water temperature can affect stable isotope ratios, we also determined whether fish length and sampling date affected the difference in isotope signatures between fins and muscle. Biopsied muscle plugs and fin clips were collected from rainbow trout Oncorhynchus mykiss, brook trout Salvelinus fontinalis, and lake trout S. namaycush as well as lake whitefish Coregonus clupeaformis and pygmy whitefish Prosopium coulterii and analyzed for stable isotopes of carbon and nitrogen. The isotope signatures of both adipose and caudal fins were significantly correlated (0.33...

The effluents from agriculture practices usually contain several contaminants creating an environmental concern to downgradient water bodies. The use of SAT systems to improve the effluents water quality, during the transport of infiltrated water through the unsaturated and saturated zones, can bring a solution for water reclamation, water reuse, and overall as a water resources management tool. The research was carried out under MARSOL project were SAT experiments were executed in a physical (sandbox) model. These experiments aimed to contribute solving the problem of removing rice field contaminants from water, using a soil-aquifer prototype basin to treat water prior to its discharge in Melides lagoon, Portugal. The sandbox model was divided into three sections to test the adsorption and biodegradation capacity of three soil profiles, two of them including soil mixtures of sand with vegetal compost with different layouts. In each section, two tracer experiments were performed wit...

Structural analysis of the High Zagros Zone and southwestern rim of the SanandajSirjan Zone in the Chaharmahal-va-Bakhtyari area resulted in recognition of a thrust system comprises the Ben, Hafshejan, Farsan, Kuhrang and Bazoft thrust sheets from NE to SW. In this study, quartz and calcite microstructures as well as fluid inclusions have been utilized to inspect deformation conditions of the thrust sheets. Microstructural study of quartz grains from the Ben and Hafshejan thrust sheets and their basal thrust zone show evidence of ductile deformation that demonstrate the deformation temperature from 250o to 350oC for the sheets. Geothermometry study of the sheets using calcite mechanical twins also reveals temperature of 250oC for the sheets. Fluid inclusions study on quartz veins from these thrust sheets display homogenization temperature up to 220oC for primary inclusions. This geothermometry survey demonstrates that physical conditions of deformation do not change significantly bu...

This study focuses on isotope characterization of groundwater in Laduba, Asa Local Government Area of Kwara State, Nigeria. Groundwater is a vital resource essential for domestic, agricultural, and industrial purposes in the region. However, there is limited information available as regards to the isotopic composition of the groundwater in the area. This study is aimed at assessing the stable its origin, recharge isotope of δ18O and deuterium signatures of groundwater to deduce information about its origin, and recharge sources. The research involves the collection of groundwater samples during which a total of twenty four (24) samples were collected from various locations within Laduba and an analysis of their isotope composition was then carried out using spectrometry techniques. The results as discussed in this study will provide valuable insights towards understanding the hydrological processes, groundwater dynamics and the vulnerability of the aquifer system in Laduba. This study will contribute to the sustainable management and utilization of groundwater resources in the area, ensuring their long-term availability and quality for various purposes.

Linked hydrochemical and isotopic studied were carried out to identify and explain the processes that control the mineralization in miopliocene aquifers in Douala basin. According to the results of the chemical analysis, the water is acidic and poor mineralized. The investigation highlights that groundwater mineralization is mainly influenced by ion exchange process, carbonate dissolution and silicate weathering. Based on isotopic signatures, shallow aquifer groundwater samples were classified into waters with depleted δ 18 O contents, highlighting the result of a rapid infiltration of local meteoric waters which has undergone a low evaporation process. Deep aquifer and some points of shallow aquifer are more enriched in 18 O than the local rains. This reflects a certain level of evaporation which the rainwater would have undergone before reaching the aquifer or the leaching of heavy isotopes accumulated in the unsaturated zone during the dry season. The relatively recent age of the waters that recharge the aquifer explains the weak action of the water-rock interaction hence the weak mineralization of the waters overall.

Whereas the presence of amino acids in fossil materials is clearly related to biosynthesis, an indigenous relationship with the fossil may be suspect. At present, attempts to establish the indigeneity of amino acids in fossils are based on distribution and stereochemistry. However, fossil systems are not closed and racemization may be retarded in organic materials within a fossil matrix. The advent of new technologies has resulted in alternative methods for evaluating the authenticity of fossil organic matter. A comparison of the stable carbon isotope compositions of the D- and L-enantiomers of individual amino acids facilitates the evaluation of indigeneity. Here we report the application of this method for determining the origin(s) of amino acids in fossils and extraterrestrial samples. Further, nitrogen isotope compositions of fossil materials should reflect trophic order, with increasing enrichment in 515N with progression up the food chain. Establishment of the trophic position...

The high P/T Catalina Schist underlies the inner southern California borderland outboard of southwestern North America and records amphibolite facies recrystallization and partial melting at ca. 115 Ma and 40 km depth. While inverted metamorphism down to lawsonite albite facies across low-angle faults has most commonly been regarded as a product of nascent subduction, new detrital zircon U-Pb ages (33 samples; N= 645) demonstrate that the Catalina Schist was derived from successively accreted sediment ...