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1.
The isotopic composition of tree ring cellulose was obtained over a 2-year period from small-diameter riparian-zone trees
at field sites that differed in source water isotopic composition and humidity. The sites were located in Utah (cool and low
humidity), Oregon (cool and high humidity), and Arizona (warm and low humidity) with source water isotope ratio values of
–125/–15‰ (δD/δ18O), –48/–6‰, and –67/–7‰, respectively. Monthly environmental measurements included temperature and humidity along with measurements
of the isotope ratios in atmospheric water vapor, stream, stem, and leaf water. Small riparian trees used only stream water
(both δD and δ18O of stem and stream water did not differ), but δ values of both atmospheric water vapor and leaf water varied substantially
between months. Differences in ambient temperature and humidity conditions between sites contributed to substantial differences
in leaf water evaporative enrichment. These leaf water differences resulted in differences in the δD and δ18O values of tree ring cellulose, indicating that humidity information was recorded in the annual rings of trees. These environmental
and isotopic measurements were used to test a mechanistic model of the factors contributing to δD and δ18O values in tree ring cellulose. The model was tested in two parts: (a) a leaf water model using environmental information
to predict leaf water evaporative enrichment and (b) a model describing biochemical fractionation events and isotopic exchange
with medium water. The models adequately accounted for field observations of both leaf water and tree ring cellulose, indicating
that the model parameterization from controlled experiments was robust even under uncontrolled and variable field conditions.
Received: 7 April 1999 / Accepted: 8 December 1999 相似文献
2.
We conducted stable oxygen and carbon isotope analyses for otoliths of Atlantic salmon (Salmo salar), in an attempt to develop a reference database on isotopic variability among private and federal hatcheries in Maine which
currently support the salmon aquaculture industry and recovery of endangered populations. During the first phase of our study,
we collected 40–50 sagittal otoliths of juvenile Atlantic salmon from each of the five hatcheries and analyzed for stable
oxygen and carbon isotope ratios (18O/16O or δ18O, and 13C/12C or δ13C). Combination of δ18O and δ13C signatures in otoliths showed that the five hatcheries can be clearly separated and chemically distinguished. By identifying
stable isotopic variations of otoliths from different hatchery settings, we were able to establish some isotopic criteria
or standards to assign a likelihood that an individual Atlantic salmon came from a specific hatchery within the reference
database. If successful, a diagnostic tool that can provide definitive information on identification of the hatchery origin
could serve as a novel marking technique, and the chemical method may provide a more effective alternative to DNA analysis
for mixed stocks. Overall our isotopic data from otoliths support the hypothesis that there are detectable differences between
the five hatcheries, and multiple statistical analyses indicated that we can correctly distinguish individual Atlantic salmon
into a hatchery with high confidence. 相似文献
3.
Hydrogen and oxygen isotope ratios of tree-ring cellulose for riparian trees grown long-term under hydroponically controlled environments 总被引:1,自引:0,他引:1
Saplings of three riparian tree species (alder, birch and cottonwood) were grown for over 5 months in a hydroponics system
that maintained the isotopic composition of source water in six treatments, ranging from –120 to +180‰δD and –15 to +10‰δ18O. The trees were grown in two greenhouses maintained at 25°C and at either 40 or 75% relative humidity, creating differences
in transpiration rates and leaf water isotopic evaporative enrichment. The cellulose produced in the annual growth ring was
linearly related to source water with differences in both slope and offset associated with greenhouse humidity. The slope
of the isotopic composition of source water versus tree-ring cellulose was less than 1 for both δD and δ18O indicating incomplete isotopic exchange of carbohydrate substrate with xylem water during cellulose synthesis. Tests using
the outer portion of the tree-ring and new roots were similar and showed that the tree-ring values were representative of
the cellulose laid down under the imposed environmental conditions. The fraction of H and O in carbohydrate substrate that
isotopically exchange with medium water was calculated to be 0.36 and 0.42 respectively, and biochemical mechanisms for these
observed fractions are discussed. A mechanistic model of the biochemical fractionation events for both δD and δ18O leading to cellulose synthesis was robust over the wide range of cellulose stable isotope ratios. The experimental results
indicate that both water source and humidity information are indeed recorded in tree-ring cellulose. These results help to
resolve some of the disparate observations regarding the interpretation of stable isotope ratios in tree-rings found in the
literature.
Received: 4 January 1999 / Accepted: 12 August 1999 相似文献
4.
Keirith A. Snyder Robert Monnar Simon R. Poulson Peter Hartsough Franco Biondi 《Trees - Structure and Function》2010,24(3):585-595
Diurnal fluctuations of leaf water isotope ratios (δ18O and δD) were measured for Jeffrey (Pinus jeffreyi Balf.) and lodgepole (Pinus contorta Douglas ex Louden) pine. Two trees per species were sampled every few hours on 15–16 October 2005 and 19–20 June 2006. Diurnal
gas exchange was measured during the summer sampling. In fall 2005, leaf water δ18O ranged from 0.7 to 9.0‰, and leaf water δD ranged from −70 to −50‰. In summer 2006, leaf water δ18O ranged from 7.7 to 20.7‰, and leaf water δD ranged from −61 to −24‰. Diurnal variation of leaf water isotope values typically
reached a maximum in early afternoon, began decreasing around midnight, and reached a minimum in mid-morning. Both periods
showed a high degree of enrichment relative to source water, with leaf water–source water enrichments ranging up to 37.8‰
for δ18O, and up to 95‰ for δD. Leaf water enrichment varied by season with summer enrichment being greater than fall enrichment.
A steady-state model (i.e., modified Craig–Gordon modeling) for leaf water isotope compositions did not provide a good fit
to measured values of leaf water. In summer, a non-steady state model provided a better fit to the measured data than the
steady-state model. Our findings demonstrate substantial leaf water enrichment above source water and diurnal variations in
the isotopic composition of leaf water, which has application to understanding short-term variability of atmospheric gases
(water vapor, CO2, O2), climate studies based on the isotopic composition of tree rings, and ecosystem water fluxes. 相似文献
5.
M. Pełechaty K. Apolinarska A. Pukacz J. Krupska M. Siepak P. Boszke M. Sinkowski 《Hydrobiologia》2010,656(1):29-42
Stable isotope composition (δ13C and δ18O) was analysed in mineral incrustation of Chara rudis and surrounding waters. This macroalga forms dense and extensive charophyte meadows and may significantly contribute to the
calcium carbonate precipitation and deposition of marl lake sediments. The study aimed to find out if charophyte calcium carbonate
was precipitated in an isotopic equilibrium with lake water and if the precipitation was related to the environmental conditions.
Two apical internodes of 10 individuals of C. rudis were collected monthly between June and late October 2008 at three permanent study sites (1.0 m, 1.5 m and 2.0 m deep) in
a small (15.1 ha) and shallow (mean depth: 4.3 m) mid-forest lake with extensively developed charophyte meadows (Lake Jasne,
mid-Western Poland). Basic physical–chemical analyses were performed at each study site, and water samples for further laboratory
determinations, including stable isotope analyses, were collected from the above searched C. rudis stands and, simultaneously, at three comparative sites in the macrophyte-free pelagial. The difference in δ13C between incrustation and water from above C. rudis exceeded 2‰ V-PDB at each site. In the case of δ18O, it exceeded 2‰ between July and September. Accordingly, it is postulated that calcium carbonate was not precipitated in
an isotopic equilibrium with lake water. Incrustation was enriched in heavier carbon isotope, 13C, and water was enriched in 18O. δ13C of incrustation and DIC were positively correlated, whereas negative relation was found between δ18O of incrustation and water. Several dependencies were found with water chemistry above the plants. The content of mineral
incrustation in Chara dry weight had negative influence on the δ18O but not on the δ13C. Community depth, structure and PVI had no effect. No significant differences appeared between isotope composition in the
pelagic zone and Chara stands. 相似文献
6.
Stable oxygen and hydrogen isotope analyses of fossil aquatic organisms, such as the chitinous head capsules of chironomid
larvae (Chironomidae: Diptera), are promising proxies for inferring paleoecological conditions. In order for analyses of stable
oxygen (δ18O) and hydrogen isotope ratios (δ2H) of fossil chironomid head capsules to be used effectively in paleoecological research, it is necessary to understand the
factors controlling their stable oxygen and hydrogen composition. We cultured chironomid larvae in two isotopically distinct
waters under controlled, replicated laboratory conditions. Chironomid larvae were fed on identical diets, to examine the degree
to which water and diet influence the δ18O and δ2H of these organisms. We used a two-end member mixing model to determine the proportional contributions of oxygen and hydrogen
from water to the oxygen and hydrogen of chironomid larvae. Our experiment demonstrated that 69.0 ± 0.4% of oxygen and 30.8 ± 2.6%
of hydrogen in chironomid larvae are derived from habitat water. Our results show that oxygen isotopes from chironomid remains
can better constrain past habitat water isotopic changes compared to hydrogen, due to 69% of the chironomid oxygen being influenced
by habitat water. Our data add to a small but growing suite of comparative data on the sources of oxygen and hydrogen in animal
tissues, and provide the first such analyses from aquatic insects. 相似文献
7.
A 200-year coral stable oxygen isotope record from a high-latitude reef off Western Australia 总被引:4,自引:0,他引:4
H. Kuhnert J. Pätzold B. Hatcher K.-H. Wyrwoll A. Eisenhauer L. B. Collins Z. R. Zhu G. Wefer 《Coral reefs (Online)》1999,18(1):1-12
A core from a coral colony of Porites lutea was analysed for stable oxygen isotopic composition*. A 200-year proxy record of sea surface temperatures from the Houtman Abrolhos Islands off west Australia was obtained from
coral δ18O. At 29′S, the Houtman Abrolhos are the southernmost major reef complex of the Indian Ocean. They are located on the path
of the Leeuwin Current, a southward flow of warm, tropical water, which is coupled to Indonesian throughflow. Coral δ18O primarily reflects local oceanographic and climatic variability, which is largely determined by spatial variability of the
Leeuwin Current. However, coherence between coral δ18O and the current strength itself is relatively weak. Evolutionary spectral and singular spectrum analyses of coral δ18O demonstrate a high variability in spectral composition through time. Oscillations in the 5–7-y, 14–15-y, and quasi-biennial
bands reflect teleconnections of local sea surface temperature (SST) to tropical Pacific climate variability. Deviations between
local (coral-based) and regional (instrument) SST contain a cyclic component with a period of 15 y. Coral δ18O suggests a rise in SST by 0.6 ′C since AD 1944, consistent with available instrumental SST records. A long-term warming
by 1.4 ′C since AD 1795 is inferred from the coral record.
Accepted: 3 July 1998 相似文献
8.
Christina E. Reynolds-Henne Matthias Saurer Rolf T. W. Siegwolf 《Trees - Structure and Function》2009,23(4):801-811
Stable isotopic ratios integrate ecosystem variability while reflecting change in both environmental and biological processes.
At sites, where climate does not strongly limit tree growth, co-occurring trees may display large discrepancies in stable
oxygen isotopic ratios (δ18O) due to the interplay between biological processes (competition for light and nutrients, individual tree physiology, etc.)
and climate. For a better quantification of the isotope variability within and among trees, the climatic and/or individual
tree effects on seasonal δ18O variations in precipitation, soil water, leaf water and leaf organic material (whole leaf, cellulose and starch) and annual
δ18O variations in tree-ring cellulose for Fagus sylvatica (Fs), Quercus robur (Qr), Carpinus betulus (Cb) and Pinus sylvestris (Ps) were studied in a mature temperate forest in Switzerland, using a mixed linear regression model technique. Furthermore,
the influence of environmental factors on δ18O was assessed by means of three common isotope fractionation models. Our statistical analysis showed that except for Ps,
a greater portion of δ18O variance in leaf compounds can be explained by individual tree effects, compared to temperature. Concerning tree-ring cellulose,
only Fs and Ps show a significant temperature signal (maximum 12% of the variance explained), while the individual tree effect
significantly explains δ18O for all species for a period of 38 years. Large species differences resulted in a limited ability of the isotope fractionation
models to predict measured values. Overall, we conclude that in a diverse mixed forest stand, individual tree responses reduce
the potential extraction of a temperature signal from δ18O. 相似文献
9.
Tracing the Sources of Exported Nitrate in the Turkey Lakes Watershed Using 15N/14N and 18O/16O isotopic ratios 总被引:3,自引:0,他引:3
John Spoelstra Sherry L. Schiff Richard J. Elgood Ray G. Semkin Dean S. Jeffries 《Ecosystems》2001,4(6):536-544
Nitrate produced by bacterially mediated nitrification in soils is isotopically distinct from atmospheric nitrate in precipitation.
15N/14N and 18O/16O isotopic ratios of nitrate can therefore be used to distinguish between these two sources of nitrate in surface waters and
groundwaters. Two forested catchments in the Turkey Lakes Watershed (TLW) near Sault Ste. Marie, Ontario, Canada were studied
to determine the relative contributions of atmospheric and microbial nitrate to nitrate export. The TLW is reasonably undisturbed
and receives a moderate amount of inorganic nitrogen bulk deposition (8.7 kg N · ha−1· yr−1) yet it exhibits unusually low inorganic nitrogen retention (average = 65% of deposition). The measured isotopic ratios for
nitrate in precipitation ranged from +35 to +59‰ (VSMOW) for δ18O and −4 to +0.8‰ (AIR) for δ15N. Nitrate produced from nitrification at the TLW is expected to have an average isotope value of approximately −1.0‰ for
δ18O and a value of about 0 to +6‰ for δ15N, thus, the isotopic separation between atmospheric and soil sources of nitrate is substantial. Nitrate produced by nitrification
of ammonium appears to be the dominant source of the nitrate exported in both catchments, even during the snowmelt period.
These whole catchment results are consistent with the results of small but intensive plot scale studies that have shown that
the majority of the nitrate leached from these catchments is microbial in origin. The isotopic composition of stream nitrate
provides information about N-cycling in the forested upland and riparian zones on a whole catchment basis.
Received 5 October 1999; accepted 18 August 2000 相似文献
10.
The stable oxygen isotope (δ
18O) composition of Austrocedrus chilensis (D. Don) Endl. (Cupressaceae) tree rings potentially provide retrospective views of changes in environment and climate in the semi-arid lands of Patagonia. We report the development of the first annually resolved δ
18O tree-ring chronology obtained from natural forests of the foothills of the northwestern Patagonian Andes. The isotope record spans between 1890 and 1994 AD. We explore the probable links between this record and the climate of the region. Air temperatures during summer conditions are significantly, but not strongly, inversely correlated with annual δ
18O values from Austrocedrus tree rings. The strongest correlations are between the southern oscillation index (SOI) and the tree rings. The existence of millennial-age Austrocedrus trees in northern Patagonia provides interesting possibilities for examining these climate-related isotopic signals over most of the last 1,000 years. 相似文献
11.
Richard J. Pruell Bryan K. Taplin Jonathan D. Karr 《Environmental Biology of Fishes》2012,93(1):61-71
Isotopic ratios of fish otoliths have been used in numerous studies as natural tags or markers to aid in the study of connectivity
among fish populations. We investigated the use of spatial and temporal changes in the stable carbon and oxygen isotope ratios
of otoliths to differentiate juvenile habitats of winter flounder (Pseudopleuronectes americanus). Young-of-the-year (YOY) juvenile winter flounder were collected annually over a three-year period from 18 stations along
the coast of Rhode Island, USA. Sagittal otoliths were removed from fish and analyzed for stable carbon (13C/12C or δ13C) and oxygen (18O/16O or δ18O) isotope ratios using continuous flow isotope ratio mass spectrometry. Differences in isotope ratios were observed among
stations and along salinity gradients in the Narragansett Bay estuary and an estuarine river system (Narrow River). Overall,
the isotope ratio patterns observed among stations were consistent over the three sampling years; however, differences were
noted in isotope ratios and the magnitude of the isotope ratio gradients among years. Significant positive correlations were
noted between salinity and δ13C for two of the three years. For each of the three years sampled there was a highly significant positive correlation (2002,
r = 0.93, P < 0.01; 2003, r = 0.85, P < 0.01; 2004, r = 0.97, P < 0.01) between δ18O and the salinity of the collection site. Also, there was a significant negative correlation between the number of months
of above average river flow and δ18O for the three sampling years (r = 0.99, P < 0.05). These findings suggest that yearly changes in the volume of freshwater inputs to these estuarine habitats may be
related to the differences observed in otolith δ18O isotope ratios. Because of these year-to-year differences, sampling of each cohort may be necessary in order to use this
isotopic technique for winter flounder connectivity studies. 相似文献
12.
Sebastian Wetterich Ulrike Herzschuh Hanno Meyer Lyudmila Pestryakova Birgit Plessen C. M. Larry Lopez Lutz Schirrmeister 《Hydrobiologia》2008,614(1):171-195
Taxonomical and geochemical investigations on freshwater ostracods from 15 waters in Central and Northeast (NE) Yakutia have
been undertaken in order to estimate their potential usefulness in palaeoenvironmental reconstructions based on regional fossil
records. Higher variability in environmental factors such as pH, electrical conductivity, and ionic content was observed in
thermokarst-affected lakes in Central Yakutia than in NE Yakutia lakes. Species diversity of freshwater ostracods reached
up to eight taxa per lake, mostly dominated by Candona weltneri Hartwig 1899, in Central Yakutia, whereas in NE Yakutian waters the diversity was lower and Candona muelleri jakutica Pietrzeniuk 1977 or Fabaeformiscandona inaequivalvis (Sars 1898) had highest frequencies. Coupled analyses of stable isotopes (δ18O, δ13C) and element ratios (Sr/Ca, Mg/Ca) were performed on both host waters and ostracod calcite, aiming to estimate the modern
relationships. Correlations between host waters and ostracod calcite of single species were found for δ18O, δ13C and Sr/Ca and Mg/Ca ratios. The relationships between δ18O, Mg/Ca and Sr/Ca ratios and electrical conductivity (salinity) as an expression of solute concentrations in the waters mainly
controlled by evaporation are more complicated but evident, and may be useful in future interpretation of geochemical data
from fossil Siberian ostracods.
Handling editor: K. Martens 相似文献
13.
Stable carbon- (δ13C), nitrogen- (δ15N) and hydrogen (δD) isotope profiles in feathers of migratory Great Reed Warblers Acrocephalus
arundinaceus recaptured for 2 or more years in 6 successive years were examined to test whether the isotope profiles of individual warblers
appeared to be consistent between years. Similar isotopic signatures in successive years suggested that individual birds tended
to return and grow their feathers in Afro-tropical wintering habitats that generate similar δ13C, δ15N and δD signatures. Previous studies have shown that Great Reed Warblers exhibit strong natal and breeding philopatry, with
most of the surviving birds returning to the breeding site. The present study of feather δ13C, δ15N and δD isotopic values demonstrate the year-to-year fidelity might also include the African moulting sites in this migratory
species. 相似文献
14.
Concentration and isotopic composition (δ13C and δ18O) of ambient CO2 and water vapour were determined within a Quercus petraea canopy, Northumberland, UK. From continuous measurements made across a 36-h period from three heights within the forest canopy,
we generated mixing lines (Keeling plots) for δa
13CO2, δa C18O16O and δa H2
18O, to derive the isotopic composition of the signal being released from forest to atmosphere. These were compared directly
with measurements of different respective pools within the forest system, i.e. δ13C of organic matter input for δa
13CO2, δ18O of exchangeable water for δa C18O16O and transpired water vapour for δa H2
18O. [CO2] and δa
13CO2 showed strong coupling, where the released CO2 was, on average, 4 per mil enriched compared to the organic matter of plant material in the system, suggesting either fractionation
of organic material before eventual release as soil-respired CO2, or temporal differences in ecosystem discrimination. δa C18O16O was less well coupled to [CO2], probably due to the heterogeneity and transient nature of water pools (soil, leaf and moss) within the forest. Similarly,
δa H2
18O was less coupled to [H2O], again reflecting the transient nature of water transpired to the forest, seen as uncoupling during times of large changes
in vapour pressure deficit. The δ18O of transpired water vapour, inferred from both mixing lines at the canopy scale and direct measurement at the leaf level,
approximated that of source water, confirming that an isotopic steady state held for the forest integrated over the daily
cycle. This demonstrates that isotopic coupling of CO2 and water vapour within a forest canopy will depend on absolute differences in the isotopic composition of the respective
pools involved in exchange and on the stability of each of these pools with time.
Received: 21 March 1998 / Accepted: 10 December 1998 相似文献
15.
Jörn Peckmann James L. Goedert Till Heinrichs Jochen Hoefs Joachim Reitner 《Facies》2003,48(1):241-253
The Late Eocene ‘Whiskey Creek’ deposit (Pysht Formation, Olympic Penisula, Washington State) formed at a methane-seep. Early
diagenetic micrites and aragonite cement have δ13C values as low as −36‰ indicating that the seepage fluids contained methane. With respect to micrite samples, low δ13C values correlate with relatively high δ13O values andvice versa. Ongoing micrite formation after the cessation of the seepage during increased burial might have altered the isotopic composition
of the microcrystalline carbonates toward lower δ13O values and higher δ13C values. Alternatively, the trend in isotope values may reflect a change in the composition of seepage fluids. The principal
difference between these scenarios is the duration of seepage with respect to micrite formation. Two petrographically similar
varieties of blocky calcite spar are related to different carbonate sources. The δ13C values range from −32 to −29‰ for one type of blocky spar and are either the result of methane oxidation or indicate thermal
decarboxylation of organic matter. Low δ18O values are in favour of the latter. For the other type of spar, δ13C values as high as +6‰ indicate carbonate formation within the zone of methanogensis.
The ‘Whiskey Creek’ limestone exhibits a chaotic fabric produced by a variety of processes, including bioturbation, concretionary
carbonate formation, earlyin situ brecciation, carbonate corrosion, and late fracturing of the rock. Two varieties of micrite aggregates are responsible for
the nodular fabric of the limestone. Smoothly-shaped pyritiferous micrite nodules are of diagenetic origin and formed in a
manner similar to that which produces carbonate concretions. Apart from being induced by anaerobic oxidation of methane, their
formation is proposed to be linked to iron reduction and sulphide formation. The second, dominant variety is represented by
irregularly-shaped, nodular to angular micrite aggregates surrounded by massive rims of pyrite, resulting from carbonate corrosion.
A pure, fluorescent seam-micrite, constructive in origin, lines cavities or surrounds micritic aggregates. 相似文献
16.
The stable carbon and oxygen isotope ratios in cellulose of C3 and C4 plants growing on the surface of a montane peat bog
in the Nilgiri hills, southern India, were measured. The mean monthly δ13C values in cellulose of both C3 and C4 plants are found to be significantly related to rainfall, while the δ18O values are sensitive to changes in maximum temperature and relative humidity of the region. Further, higher δ18O values were observed in C4 plants compared to C3 plants, suggesting that C4 plants are probably less sensitive to relative
humidity as compared to C3 plants and are able to photosynthesize even during drier conditions. The plant isotope-climate
correlations thus established can be used for reconstructing the past temperature and rainfall conditions of the tropics from
the isotopic ratios of peat deposits, derived from a mixture of C3 and C4 plants in the region. 相似文献
17.
Oxygen (O) and sulfur (S) isotope systematics in bog water sulfates were determined for six Sphagnum dominated wetlands located in the British Isles and the Czech Republic, Central Europe. Comparison of a polluted and unpolluted
site showed that 4 times higher atmospheric S inputs led to 3 times higher bog water sulfate concentrations and substrate
S concentrations, 3 times increased ranges of substrate S concentrations, and 3 times increased ranges of δ34S values. Sites with elevated atmospheric S inputs exhibited greater geochemical variability in wetland S species. Sulfate
O–S isotope composition of bog pore water at a depth of 40 cm below surface differed from that of surface bog water, indicating
that dissimilatory bacterial sulfate reduction, a process known to discriminate against the heavier isotopes 18O and 34S, occurred in surface peat layers. While bacterial sulfate reduction remained to be one of the main isotope-selective processes
for sulfate in peat, it could not fully explain the O–S isotope systematics of peat waters. The ‘residual’ sulfate was not
simultaneously enriched in the heavier isotopes 18O and 34S. Mixing of residual sulfate following bacterial sulfate reduction with the product of S2− reoxidation, cleavage of esters, and isotope exchange reactions may have contributed to the decoupling of the δ34Sso4 and δ18Sso4 values. Large within-site differences in δ18Sso4 and δ34Sso4 (up to 13 and 15‰, respectively) indicated little communication between the 0 and 40 cm peat depth at some sites. Extremely
high δ18Sso4 and δ34Sso4 values found in several peat bog water samples from Connemara (Ireland), Thorne Moors (England) and Ocean (Czech Republic)
were not seen in streams draining the wetlands. Direct runoff of atmogenic sulfate constituted a significant portion of the
bog outflow. At the wetland scale, zones of dissimilatory bacterial sulfate reduction form pockets whose lateral hydrological
fluxes are small. 相似文献
18.
Franck Lartaud Laurent Emmanuel Marc de Rafelis Michel Ropert Nathalie Labourdette Christopher A. Richardson Maurice Renard 《Facies》2010,56(1):13-25
Cathodoluminescence (CL) microscopy of the foliated calcite shell hinge sections of live-collected oyster Crassostrea gigas collected at seven locations along a latitudinal gradient from the Netherlands in the North Sea to the Atlantic coast of
France, revealed variations in luminescence that were attributable to seasonal variations in calcification of the hinge. Photomicrographs
of hinge sections and luminescence profiles were analyzed to define a micro-sampling strategy that was adopted to drill the
hinge samples to determine their isotopic composition. Reconstructed seasonal seawater temperatures determined from the stable
oxygen isotope (δ18O) composition along growth profiles from 32 oyster shell hinges showed distinct seasonal isotopic cycles that were compared
with in situ measured seawater temperatures and salinities at each location. Comparison of the amplitude of the (δ18O) signal and the annual maximum and minimum seawater temperatures demonstrated that C. gigas shells from several locations provided a reliable record of seasonal seawater temperature variation. The exception to this
was oysters from the Netherlands and northern France where winter growth rates at low temperatures were slow so that insufficient
shell was deposited to allow adequate spatial resolution of sampling and this resulted in time-averaging of the reconstructed
seawater temperatures and an overestimation of winter seawater temperature. A potential variability in δ18Ow–salinity relationship at low salinities could also explain the high difference between measured and predicted seawater temperatures
in Dutch areas. The finding that latitudinal differences in oyster hinge growth rates and/or changes in the δ18Ow–salinity relationship can result in bias of the seawater temperature deduced from the stable isotopic composition of the
hinge should be taken into account when reconstructing latitudinal gradients in seawater temperature. 相似文献
19.
C. P. Chamberlain J. D. Blum R. T. Holmes Xiahong Feng T. W. Sherry G. R. Graves 《Oecologia》1996,109(1):132-141
To determine whether stable isotopes can be used for identifying the geographic origins of migratory bird populations, we
examined the isotopic composition of hydrogen (deuterium, δD), carbon (δ13C), and strontium (δ87Sr) in tissues of a migratory passerine, the black-throated blue warbler (Dendroica caerulescens), throughout its breeding range in eastern North America. δD and δ13C values in feathers, which are grown in the breeding area, varied systematically along a latitudinal gradient, being highest
in samples from the southern end of the species’ breeding range in Georgia and lowest in southern Canada. In addition, δD
decreased from east to west across the northern part of the breeding range, from New Brunswick to Michigan. δ87Sr ratios were highest in the Appalachian Mountains, and decreased towards the west. These patterns are consistent with geographical
variation in the isotopic composition of the natural environment, i.e., with that of precipitation, plants, and soils for
δD, δ13C, and δ87Sr, respectively. Preliminary analyses of the δD and δ13C composition of feathers collected from warblers in their Caribbean winter grounds indicate that these individuals were mostly
from northern breeding populations. Furthermore, variances in isotope ratios in samples from local areas in winter tended
to be larger than those in summer, suggesting that individuals from different breeding localities may mix in winter habitats.
These isotope markers, therefore, have the potential for locating the breeding origins of migratory species on their winter
areas, for quantifying the degree of mixing of breeding populations on migratory and wintering sites, and for documenting
other aspects of the population structure migratory animals – information needed for studies of year-round ecology of these
species as well as for their conservation. Combining information from several stable isotopes will help to increase the resolution
for determining the geographic origins of individuals in such highly vagile populations.
Received: 24 April 1995 / Accepted: 2 June 1996 相似文献
20.
Stable isotopes (δD and δ13C) are geographic indicators of natal origins of monarch butterflies in eastern North America 总被引:1,自引:0,他引:1
Wing membranes of laboratory and field-reared monarch butterflies (Danaus plexippus) were analyzed for their stable-hydrogen (δD) and carbon (δ13C) isotope ratios to determine whether this technique could be used to identify their natal origins. We hypothesized that
the hydrogen isotopic composition of monarch butterfly wing keratin would reflect the hydrogen isotope patterns of rainfall
in areas of natal origin where wings were formed. Monarchs were reared in the laboratory on milkweed plants (Asclepias sp.) grown with water of known deuterium content, and, with the assistance of volunteers, on native milkweeds throughout
eastern North America. The results show that the stable hydrogen isotopic composition of monarch butterflies is highly correlated
with the isotopic composition of the milkweed host plants, which in turn corresponds closely with the long-term geographic
patterns of deuterium in rainfall. Stable-carbon isotope values in milkweed host plants were similarly correlated with those
values in monarch butterflies and showed a general pattern of enrichment along a southwest to northeast gradient bisecting
the Great Lakes. These findings indicate that natal origins of migratory and wintering monarchs in Mexico can be inferred
from the combined δD and δ13C isotopic signatures in their wings. This relationship establishes that analysis of hydrogen and carbon isotopes can be used
to answer questions concerning the biology of migratory monarch butterflies and provides a new approach to tracking similar
migratory movements of other organisms.
Received: 1 July 1998 / Accepted: 11 November 1998 相似文献