Microsampling technique for stable isotopic analyses of carbonates

1980 ◽  
Vol 50 (2) ◽  
pp. 643-644 ◽  
Author(s):  
D. Prezbindowski
Keyword(s):  
Isotopic Analyses ◽  
Stable Isotopic

Stable isotopes in planktonic and benthic foraminifera from Arctic Ocean surface sediments

1988 ◽  
Vol 25 (5) ◽  
pp. 701-709 ◽  
Author(s):  
A. E. Aksu ◽  
G. Vilks
Keyword(s):  
Surface Water ◽  
Arctic Ocean ◽  
Sea Water ◽  
Ocean Surface ◽  
The Arctic ◽  
Size Fractions ◽  
Isotopic Compositions ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Surface Water Salinity

Oxygen and carbon isotopic analyses have been performed on the tests of Planulina wuellerstorfi and three size fractions of sinistral Neogloboquadrina pachyderma recovered from 33 Arctic Ocean surface-sediment samples. Stable isotopic compositions of N. pachyderma are found to be dependent on the test size: larger specimens show considerable enrichment in both δ18O and δ18C. The difference between the isotopic compositions of the 63–125 and 125–250 μm size fractions in N. pachyderma can be explained by biogenic fractionation effects during foraminiferal test growth. Larger (250–500 μm) N. pachyderma displayed accretions of secondary calcite, i.e., the outermost shell contained significant amounts of inorganically precipitated magnesium calcite. Thus, larger foraminifera may not be suited for down-core stable isotopic studies. There is a difference of ~2‰ between δ18O values of surface samples from the eastern and western Arctic Ocean, reflecting large differences between surface-water salinity in these regions. Therefore, oxygen isotopic data may have limited use as a chronostratigraphic tool in down-core studies in the Arctic Ocean, but we can use them to infer past variations in surface-water salinities. Planulina wuellerstorfi also showed depletions of both δ18O and δ18C in its calcite tests relative to calcite precipitated in isotopic equilibrium with ambient sea water; these depletions ranged from −0.8 to −0.9‰ in δ18Oand −1.2 to −0.9‰ in δ18C. This taxon is found to deposit its shell very close to the δ18C of ΣCO2 of bottom waters.

Tracing the geographical origin of rice by stable isotopic analyses combined with chemometrics

2020 ◽  
Vol 313 ◽  
pp. 126093 ◽  
Author(s):  
Jishi Wang ◽  
Tianjin Chen ◽  
Weixing Zhang ◽  
Yan Zhao ◽  
Shuming Yang ◽  
...  
Keyword(s):  
Geographical Origin ◽  
Isotopic Analyses ◽  
Stable Isotopic

Investigating the permeability of fractured rock masses and the origin of water in a mine tunnel in Shandong Province, China

2015 ◽  
Vol 72 (11) ◽  
pp. 2006-2017 ◽  
Author(s):  
Jie Guo ◽  
Haijun Zhao ◽  
Fengshan Ma ◽  
Kepeng Li ◽  
Chunhu Zhao
Keyword(s):  
Isotope Composition ◽  
Fractured Rock ◽  
Atmospheric Precipitation ◽  
Seepage Water ◽  
Rock Masses ◽  
Saline Groundwater ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Fractured Rock Masses ◽  
Different Sources

The coastal Sanshandao mine is threatened by the overlying Quaternary water and seawater. Following an introduction to the geology and hydrogeological conditions in the mine area, a detailed hydrogeological survey and sampling were conducted and hydrochemical and stable isotopic (δ2H and δ18O) tests on various waters were carried out to characterize the origin of water in the mine tunnels. Investigation and statistical analysis indicated that the northwest-trending fractures with large dip angles and long trace lengths are well developed in the northeast compared with those in the southwest of the mine. The permeability coefficients of the rock masses are in the range 4.19 × 10−8–2.25 × 10−5 m/s, indicating that the fractured rock masses have generally low permeability. The seepage water had higher values of EC, total dissolved solids, and concentrations of most elements than the seawater and saline groundwater. Besides, the isotope composition of the waters indicated that the seepage water was more isotopically enriched than seawater but less than brine. The proportions of the three different sources were calculated based on hydrochemical and isotopic analyses. Overall, the mine water was composed of 72% seawater, 14.8% brine, and 13.2% atmospheric precipitation, respectively. Therefore, some preventive measures are essential to avoid the probability of seawater inrush.

scholarly journals Stable isotopic composition of top consumers in Arctic cryoconite holes: revealing different position in supraglacial trophic network

2020 ◽  
Author(s):  
Tereza Jaroměřská ◽  
Jakub Trubač ◽  
Krzysztof Zawierucha ◽  
Lenka Vondrovicová ◽  
Miloslav Devetter ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Hot Spots ◽  
High Arctic ◽  
Biological Processes ◽  
Trophic Relations ◽  
Glacier Surface ◽  
Δ13c Values ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Trophic Network

Abstract. Cryoconite holes are ecosystems on the glacier surface characterized by dynamic nature and truncated food webs. It is acknowledged that cryoconite holes play an important role being biodiversity hot-spots and factories for organic matter on glaciers. The most common cryoconite apex consumers are the cosmopolitan invertebrates – tardigrades and rotifers. Several studies have highlighted the relevance of cryoconite tardigrades and rotifers to cryoconite holes’ ecosystem functioning. However, due to the dominant occurrence of prokaryotes on glaciers, these consumers are usually out of the major scope of most studies aiming at biological processes on glaciers. The aim of this study is to present data about isotopic composition of tardigrades, rotifers and cryoconite from three High Arctic glaciers in Svalbard and discuss their potential trophic relations. We found that tardigrades have lower δ15N values than rotifers, which indicates different food requirements of both consumers. The δ13C values revealed similarities among the consumers from the same glaciers and differences between consumers and cryoconite among glaciers. The resulted δ13C values point to similar carbon requirement of consumers within a glacier but differences in carbon input between glaciers. The results comprise the first observation of cryoconite holes’ consumers through stable isotopic analyses using an improved method of cryoconite sample processing and pave the way for further studies of the supraglacial trophic network.

Feeding habits of the short-finned squidIllex coindetiiin the western Mediterranean Sea using combined stomach content and isotopic analysis

2015 ◽  
Vol 96 (6) ◽  
pp. 1235-1242 ◽  
Author(s):  
Francisco Martínez-Baena ◽  
Joan Navarro ◽  
Marta Albo-Puigserver ◽  
Isabel Palomera ◽  
Rigoberto Rosas-Luis
Keyword(s):  
Mediterranean Sea ◽  
Stomach Content ◽  
Feeding Habits ◽  
Western Mediterranean ◽  
Trophic Levels ◽  
Mesopelagic Fish ◽  
Western Mediterranean Sea ◽  
Isotopic Analyses ◽  
Stable Isotopic ◽  
Prey Items

The ommastrephid squid,Illex coindetii, is one of the most abundant cephalopods in the Mediterranean Sea and an important predator in the ecosystem. In the present study, we examined the diet habits ofI. coindetiiin the north-western Mediterranean Sea by combining two complementary approaches: stomach content and stable isotopic analyses. Specifically, we examined whether the diet differed between sizes and seasons. Stomach content results indicated that the diet ofI. coindetiiwas composed of 35 prey items including four major groups; namely the crustaceansPasiphaea sivado, Amphipods, squid of the Order Teuthida, and pelagic and mesopelagic fish. Differences were found among different ontogenetic sizes: juvenile individuals fed mainly on crustaceans (%IRI = 77.59), whereas adult individuals fed on a wider range of prey items, including the shrimpP. sivado(%IRI = 33.21), the amphipodAnchylomera blossevillei(%IRI = 0.91), the decapodPlesionikasp. (%IRI = 0.19), the carangidTrachurus trachurus(%IRI = 0.34) and some Myctophids species (%IRI = 0.21). Differences were also found between seasons in the year. In winter, crustaceans were the main prey items, whereas in summer the diversity of prey was higher, including fish, crustaceans and molluscs. Similar to the stomach contents, stable isotopic results indicated differences among sizes. δ15N values were higher in adult squids than in juveniles because they fed on prey at higher trophic levels. In conclusion, this study indicates that feeding habits ofI. coindetiivary seasonally and ontogenetically. These feeding variations may be associated with trophic competence scenarios based on size, and also with the availability and abundance of prey throughout the year.

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