scholarly journals Global trends in novel stable isotopes in basalts: theory and observations

2021 ◽  
Author(s):  
Caroline Soderman ◽  
Oliver Shorttle ◽  
Simon Matthews ◽  
Helen Williams
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Isotopic Composition ◽  
Isotope Fractionation ◽  
Isotopic Fractionation ◽  
Isotope Ratios ◽  
Analytical Precision ◽  
Natural Data ◽  
The Mean ◽  
Lithological Heterogeneity

The geochemistry of global mantle melts suggests that both mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) sample lithological and temperature heterogeneities originating in both the upper and lower mantle. Recently, non-traditional stable isotopes have been suggested as a new tool to complement existing tracers of mantle heterogeneity (e.g., major and trace elements, radiogenic isotopes), because mineral- and redox-specific equilibrium stable isotope fractionation effects can link the stable isotope ratios of melts to their source mineralogy and melting degree. Here, we investigate five stable isotope systems (Mg-Ca-Fe-V-Cr) that have shown promise in models or natural samples as tracers of mantle temperature and/or lithological heterogeneity. We use a quantitative model, combining thermodynamically self-consistent mantle melting and equilibrium isotope fractionation models, to explore the behaviour of the isotope ratios of these elements during melting of three mantle lithologies (peridotite, and silica-excess and silica-deficient pyroxenites), responding to changes in mantle mineralogy, oxygen fugacity, temperature and pressure.We find that, given current analytical precision, the stable isotope systems examined here are not predicted to be sensitive to mantle potential temperature variations through equilibrium isotope fractionation processes. By contrast, source lithological heterogeneity is predicted to be detectable in some cases in the stable isotope ratios of erupted basalts, although generally only at proportions of > 10% MORB-like pyroxenite in the mantle source, given current analytical precision. Magnesium and Ca stable isotopes show most sensitivity to a garnet-bearing source lithology, and Fe and Cr stable isotopes are potentially sensitive to the presence of MORB-like pyroxenite in the mantle source, although the behaviour of Cr isotopes is comparatively under-constrained and requires further work to be applied with confidence to mantle melts. When comparing the magnitude and direction of predicted equilibrium isotopic fractionation of peridotite and pyroxenite melts to natural MORB and OIB data, we find that aspects of the natural data (including the mean Mg-Ca-Fe-V isotopic composition of MORB, the range of Mg-Ca isotopic compositions seen in MORB data, the mean Mg-Ca-Cr isotopic composition of OIB, and the range of Mg-V-Cr isotopic compositions in OIB data) can be matched by equilibrium isotope fractionation during partial melting of peridotite and pyroxenite sources -- with pyroxenite required even for some MORB data. However, even when considering analytical uncertainty on natural sample measurements, the range in stable isotope compositions seen across the global MORB and OIB datasets suggests that kinetic isotope fractionation, or processes modifying the isotopic composition of recycled crustal material such that it is distinct from MORB, may be required to explain all the natural data. We conclude that the five stable isotope systems considered here have potential to be powerful complementary tracers to other geochemical tracers of the source lithology of erupted basalts. However, continued improvements in analytical precision in conjunction with experimental and theoretical predictions of isotopic fractionation between mantle minerals and melts are required before these novel stable isotopes can be unambiguously used to understand source heterogeneity in erupted basalts.

scholarly journals Characterisation of stable isotopes to identify residence times and runoff components in two meso-scale catchments in the Abay/Upper Blue Nile basin, Ethiopia

2014 ◽  
Vol 18 (6) ◽  
pp. 2415-2431 ◽  
Author(s):  
S. Tekleab ◽  
J. Wenninger ◽  
S. Uhlenbrook
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Isotopic Composition ◽  
Residence Times ◽  
Nile Basin ◽  
Blue Nile ◽  
Source Areas ◽  
Blue Nile Basin ◽  
Mean Residence Times ◽  
Meso Scale

Abstract. Measurements of the stable isotopes oxygen-18 (18O) and deuterium (2H) were carried out in two meso-scale catchments, Chemoga (358 km2) and Jedeb (296 km2) south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin, as more than 70% of total Nile water flow originates from the Ethiopian highlands. Stable isotope compositions in precipitation, spring water and streamflow were analysed (i) to characterise the spatial and temporal variations of water fluxes; (ii) to estimate the mean residence time of water using a sine wave regression approach; and (iii) to identify runoff components using classical two-component hydrograph separations on a seasonal timescale. The results show that the isotopic composition of precipitation exhibits marked seasonal variations, which suggests different sources of moisture generation for the rainfall in the study area. The Atlantic–Indian Ocean, Congo basin, Upper White Nile and the Sudd swamps are the potential moisture source areas during the main rainy (summer) season, while the Indian–Arabian and Mediterranean Sea moisture source areas during little rain (spring) and dry (winter) seasons. The spatial variation in the isotopic composition is influenced by the amount effect as depicted by moderate coefficients of determination on a monthly timescale (R2 varies from 0.38 to 0.68) and weak regression coefficients (R2 varies from 0.18 to 0.58) for the altitude and temperature effects. A mean altitude effect accounting for −0.12‰/100 m for 18O and −0.58‰/100 m for 2H was discernible in precipitation isotope composition. Results from the hydrograph separation on a seasonal timescale indicate the dominance of event water, with an average of 71 and 64% of the total runoff during the wet season in the Chemoga and Jedeb catchments, respectively. Moreover, the stable isotope compositions of streamflow samples were damped compared to the input function of precipitation for both catchments. This damping was used to estimate mean residence times of stream water of 4.1 and 6.0 months at the Chemoga and Jedeb catchment outlets, respectively. Short mean residence times and high fractions of event water components recommend catchment management measures aiming at reduction of overland flow/soil erosion and increasing of soil water retention and recharge to enable sustainable development in these agriculturally dominated catchments.

Stable isotopes in jumbo squid (Dosidicus gigas) beaks to estimate its trophic position: comparison between stomach contents and stable isotopes

2006 ◽  
Vol 86 (2) ◽  
pp. 437-445 ◽  
Author(s):  
R.I. Ruiz-Cooley ◽  
Unai Markaida ◽  
D. Gendron ◽  
S. Aguíñiga
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Trophic Position ◽  
Stomach Contents ◽  
Isotope Ratios ◽  
Trophic Relationships ◽  
Dosidicus Gigas ◽  
Jumbo Squid ◽  
C And N ◽  
Biomass Increase

Stomach contents and carbon (C) and nitrogen (N) stable isotope analysis were used to evaluate trophic relationships of jumbo squid, Dosidicus gigas. Buccal masses, beaks and stomach contents of large and medium maturing-sized jumbo squid and muscle from its main prey, the myctophid Benthosema panamense, were collected in the Gulf of California, Mexico during 1996, 1997 and 1999. Both the quantified C and N-isotope ratios in muscle, and stomach content analysis revealed that larger-sized maturing squid showed a higher trophic position than medium-sized individuals. However, a discrepancy between stomach contents versus stable isotope analyses was found in evaluating trophic relationships. Simple dilution models as a function of growth were used to estimate the C and N renewal dietary shift for jumbo squid. Estimates of the initial C and N pools in D. gigas with an initial age of 70 days and 210 days indicated isotopic shifts of 32% after a threefold biomass increase and 25% after a fourfold biomass increase, respectively. Additionally, beak samples of jumbo squid were evaluated as an alternative tissue to estimate squid trophic position using stable isotopes. The results showed a significant correlation between stable isotope ratios from muscle and beak samples. Muscle isotope values were higher than beak by 1% and 4% for δ13C and δ15N respectively. A test with jumbo squid beaks collected from a stomach of a stranded sperm whale confirmed the viability of this method.

Stable isotopes of carbon and nitrogen in the study of avian and mammalian trophic ecology

2000 ◽  
Vol 78 (1) ◽  
pp. 1-27 ◽  
Author(s):  
Jeffrey F Kelly
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Carbon Isotope ◽  
Isotope Ratio ◽  
Trophic Ecology ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Food Chains ◽  
Stable Isotope Ratios ◽  
Carbon And Nitrogen

Differential fractionation of stable isotopes of carbon during photosynthesis causes C4 plants and C3 plants to have distinct carbon-isotope signatures. In addition, marine C3 plants have stable-isotope ratios of carbon that are intermediate between C4 and terrestrial C3 plants. The direct incorporation of the carbon-isotope ratio (13C/12C) of plants into consumers' tissues makes this ratio useful in studies of animal ecology. The heavy isotope of nitrogen (15N) is preferentially incorporated into the tissues of the consumer from the diet, which results in a systematic enrichment in nitrogen-isotope ratio (15N/14N) with each trophic level. Consequently, stable isotopes of nitrogen have been used primarily to assess position in food chains. The literature pertaining to the use of stable isotopes of carbon and nitrogen in animal trophic ecology was reviewed. Data from 102 studies that reported stable-isotope ratios of carbon and (or) nitrogen of wild birds and (or) mammals were compiled and analyzed relative to diet, latitude, body size, and habitat moisture. These analyses supported the predicted relationships among trophic groups. Carbon-isotope ratios differed among species that relied on C3, C4, and marine food chains. Likewise, nitrogen-isotope ratios were enriched in terrestrial carnivorous mammals relative to terrestrial herbivorous mammals. Also, marine carnivores that ate vertebrates had nitrogen-isotope ratios that were enriched over the ratios of those that ate invertebrates. Data from the literature also indicated that (i) the carbon-isotope ratio of carnivore bone collagen was inversely related to latitude, which was likely the result of an inverse relationship between the proportion of carbon in the food chain that was fixed by C4 plants and latitude; (ii) seabirds and marine mammals from northern oceans had higher nitrogen-isotope ratios than those from southern oceans; (iii) the nitrogen-isotope ratios of terrestrial mammals that used xeric habitats were higher than the ratios of those that used mesic habitats, indicating that water stress can have important effects on the nitrogen-isotope ratio; (iv) there was no relationship between body mass and nitrogen-isotope ratio for either bone collagen or muscle of carnivores; and (v) there was linear covariation between stable-isotope ratios of carbon and nitrogen in marine food chains (but not in terrestrial C3 or C4 food chains), which is likely a product of increases in carbon-isotope ratio with trophic level in marine food chains. Differences in stable-isotope composition among trophic groups were detected despite variation attributable to geographic location, climate, and analytical techniques, indicating that these effects are large and pervasive. Consequently, as knowledge of the distribution of stable isotopes of carbon and nitrogen increases, they will probably become an increasingly important tool in the study of avian and mammalian trophic ecology.

Biology and Management of Dogfish Sharks

2009 ◽  
Keyword(s):  
Stable Isotope ◽  
Pacific Ocean ◽  
Food Webs ◽  
Trophic Position ◽  
Nitrogen Isotope ◽  
Isotope Ratios ◽  
Gulf Of Alaska ◽  
The North ◽  
Northeastern Pacific ◽  
The Mean

Abstract.—Spiny dogfish <em>Squalus acanthias </em>biomass has increased in the Gulf of Alaska, yet little is known about the ecological niche that dogfish fill in this ecosystem. Trophic position is an important indicator of the ecological role of an organism. To explore the trophic position of dogfish we analyzed the nitrogen and carbon stable isotope ratios of 60 dogfish from five locations between Washington and the Gulf of Alaska. The mean δ<sup>15</sup>N values for dogfish ranged from 12.0‰ (central Gulf of Alaska) to 13.4‰ (Howe Sound, British Columbia) and the mean δ<sup>13</sup>C values ranged from –21.3‰ (Yakutat Bay, Alaska) to –17.9‰ (Puget Sound, Washington). Sites to the north tended to be significantly depleted in the heavy isotopes of both nitrogen and carbon. The differences in nitrogen isotope ratios among sites were attributed to potential changes in dogfish feeding behavior and trophic position. Differences in carbon isotope ratios suggested that dogfish utilize different food webs along the northeastern Pacific Ocean shelf. Additionally it was hypothesized that feeding differentially in offshore versus inshore food webs or targeting pelagic versus benthic prey species may explain the isotopic variability. These results are preliminary and require additional tests before conclusions can be made about the trophic position of dogfish in this region. Future work will explore stable isotope variability at lower trophic levels to test the hypothesis that entire food webs are isotopically shifted owing to differences in isotopic fractionation at the base of the food web. Also, trophic level differences among dogfish size classes and between sexes will be explored among a greater diversity of locations to better describe the ecological consequences of increased biomass of dogfish in the northeastern Pacific Ocean.

scholarly journals Stable isotope (C, N, O, and H) study of a comprehensive set of feathers from two Setophaga citrina

2020 ◽  
Author(s):  
Samiksha Deme ◽  
Laurence Y. Yeung ◽  
Tao Sun ◽  
Cin-Ty A. Lee
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Isotopic Composition ◽  
Neotropical Migrants ◽  
Nitrogen Stable Isotopes ◽  
Carbon And Nitrogen ◽  
Breeding Grounds ◽  
Hooded Warblers

AbstractOxygen, hydrogen, carbon and nitrogen stable isotopes were measured on a comprehensive sampling of feathers from two spring Hooded Warblers (Setophaga citrina) in Texas to evaluate isotopic variability between feathers and during molt. Isotopic homogeneity within each bird was found across all four isotopic systems, supporting the hypothesis that molt in these neotropical migrants is fully completed on the breeding grounds. Moreover, this homogeneity suggests that the isotopic composition of a single feather is typically representative of the whole songbird. However, each bird also has outlier feathers, which could signify regrowth of lost feathers after prebasic molt.

scholarly journals Stable isotope (C, N, O, and H) study of a comprehensive set of feathers from two Setophaga citrina

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0236536
Author(s):  
Samiksha Deme ◽  
Laurence Y. Yeung ◽  
Tao Sun ◽  
Cin-Ty A. Lee
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Isotopic Composition ◽  
Neotropical Migrants ◽  
Nitrogen Stable Isotopes ◽  
Carbon And Nitrogen ◽  
Breeding Grounds ◽  
Hooded Warblers

Oxygen, hydrogen, carbon and nitrogen stable isotopes were measured on a comprehensive sampling of feathers from two spring Hooded Warblers (Setophaga citrina) in Texas to evaluate isotopic variability between feathers and during molt. Isotopic homogeneity within each bird was found across all four isotopic systems, supporting the hypothesis that molt in these neotropical migrants is fully completed on the breeding grounds. This homogeneity suggests that the isotopic composition of a single feather is may be representative of the whole songbird. However, each bird was found to have one or two outlier feathers, which could signify regrowth of lost feathers after prebasic molt.

Stable Isotope Ratios as a Tool in Microbial Forensics—Part 1. Microbial Isotopic Composition as a Function of Growth Medium

2004 ◽  
Vol 49 (5) ◽  
pp. 1-7 ◽  
Author(s):  
Helen W. Kreuzer-Martin ◽  
Lesley A. Chesson ◽  
Michael J. Lott ◽  
Janet V. Dorigan ◽  
James R. Ehleringer
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Growth Medium ◽  
Isotope Ratios ◽  
Stable Isotope Ratios ◽  
Microbial Forensics

Stable isotope composition of walleye: 15N accumulation with age and area-specific differences in δ13C

2001 ◽  
Vol 58 (6) ◽  
pp. 1253-1260 ◽  
Author(s):  
Nathanael C Overman ◽  
Donna L Parrish
Keyword(s):  
Stable Isotope ◽  
Isotopic Composition ◽  
Carbon Isotope ◽  
Trophic Position ◽  
Isotope Composition ◽  
Isotope Analysis ◽  
Isotopic Fractionation ◽  
Stomach Content Analysis ◽  
Metabolic Effects ◽  
N Accumulation

Stable nitrogen and carbon isotope ratios were measured for walleye (Stizostedion vitreum) collected across Lake Champlain, Vermont, to determine relationships between isotopic composition and diet, location of capture, length, weight, and age. Variation in δ13C values reflected area-specific differences in isotopic composition of organisms collected across the lake. A critical assumption in the application of isotope techniques is that a predictable relationship exists between the diet and isotopic composition of an organism. Our results indicate that isotopic fractionation factors may not be independent of age as has largely been assumed. By combining stable nitrogen and carbon isotope analysis with conventional stomach content analysis, we documented significant age effects in the δ15N composition of adult walleye that were not attributable to observed changes in diet. Age accounted for 81% of the variation in δ15N values of walleye (ages 2–27, N = 65, δ15N range = 15.3–19.2‰), providing evidence supporting 15N accumulation over the life span of walleye. Therefore, the risk of making faulty inferences of trophic position and food web interactions based on δ15N values may be increased when age is unknown. Our results indicate that metabolic effects associated with age require greater consideration in applications of stable isotope analysis.

scholarly journals The O and H stable isotope composition of freshwaters in the British Isles. 2. Surface waters and groundwater

2003 ◽  
Vol 7 (2) ◽  
pp. 183-195 ◽  
Author(s):  
W. G. Darling ◽  
A. H. Bath ◽  
J. C. Talbot
Keyword(s):  
Stable Isotopes ◽  
Stable Isotope ◽  
Isotopic Composition ◽  
Surface Waters ◽  
Isotope Composition ◽  
Weighted Average ◽  
Ice Age ◽  
Annual Rainfall ◽  
British Isles ◽  
Contour Maps

Abstract. The utility of stable isotopes as tracers of the water molecule has a long pedigree. The study reported here is part of an attempt to establish a comprehensive isotopic "baseline" for the British Isles as background data for a range of applications. Part 1 of this study (Darling and Talbot, 2003) considered the isotopic composition of rainfall in Britain and Ireland. The present paper is concerned with the composition of surface waters and groundwater. In isotopic terms, surface waters (other than some upland streams) are poorly characterised in the British Isles; their potential variability has yet to be widely used as an aid in hydrological research. In what may be the first study of a major British river, a monthly isotopic record of the upper River Thames during 1998 was obtained. This shows high damping of the isotopic variation compared to that in rainfall over most of the year, though significant fluctuations were seen for the autumn months. Smaller rivers such as the Stour and Darent show a more subdued response to the balance between runoff and baseflow. The relationship between the isotopic composition of rainfall and groundwater is also considered. From a limited database, it appears that whereas Chalk groundwater is a representative mixture of weighted average annual rainfall, for Triassic sandstone groundwater there is a seasonal selection of rainfall biased towards isotopically-depleted winter recharge. This may be primarily the result of physical differences between the infiltration characteristics of rock types, though other factors (vegetation, glacial history) could be involved. In the main, however, groundwaters appear to be representative of bulk rainfall within an error band of 0.5‰ δ18O. Contour maps of the δ18O and δ2H content of recent groundwaters in the British Isles show a fundamental SW-NE depletion effect modified by topography. The range of measured values, while much smaller than those for rainfall, still covers some ‰ for δ18O and 30‰ for δ2H. Over lowland areas the "altitude effect" is of little significance, but in upland areas is consistent with a range of –0.2 to –0.3‰ per 100 m increase in altitude. Groundwaters dating from the late Pleistocene are usually modified in δ18O and δ2H owing to the effects of climate change on the isotopic composition of rainfall and thus of recharge. Contour maps of isotopic variability prior to 10 ka BP, based on the relatively limited information available from the British Isles, allow a first comparison between groundwaters now and at the end of the last Ice Age. The position of the British Isles in the context of the stable isotope systematics of NW Europe is reviewed briefly. Keywords: Stable isotopes, surfacewaters, groundwater, British Isles

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