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The study is aimed to determine the C13 and O18 isotope ratios of plant species belonging to different life forms in different forest types in Yenice Forests hot spot. Carbon and oxygen isotope ratios are important in providing long-term information about plants. In our study, we grouped the plants by considering the life forms of Raunkiaer. We determined the C13 and O18 isotope ratios of life forms in different forest layers. We found highly positive correlations (p<0.05) between δ13C and δ18O isotope ratios in beech-fir and pure oak forest habitats. In the Yenice Forests, which have a megathermal climate type, plants in different forest layers have settled in the areas by choosing the life forms where water will be used most effectively. Geophyte (-27.38±2.27 p<0.05) is the life form with the highest C13 isotope ratio in terms of life forms. This situation proves that the group that felt the water deficiency the earliest is the geophyte form. For O18 isotope ratio, therophytes using surface water are the highest (24.06±3.92 p<0.05) life forms. It is important to examine the water deficiency in old forests such as Yenice Forests through life forms. [ABSTRACT FROM AUTHOR]

The stable nitrogen and oxygen isotopic ratios (δ15N, δ18O) have been used extensively as important tools to identify nitrate sources and understand nitrogen biogeochemical cycle. The ion exchange technique, one of the most widely used analytical methods for nitrogen isotope composition of nitrate, measures oxygen isotope composition of nitrate from a solution can have a complex sample preparation procedure and time-consuming (3~5 days) that have restricted their application in the laboratory. Here we propose an improved method of ion exchange to measure δ18O of NO3-, which utilizes BaCl₂ to remove non-nitrate oxygen-bearing anions (SO42- and PO43-) in the first step. followed by a collected of water nitrate with an anion exchange column, eluted with HCl, then neutralized with Ag₂O to obtain solid AgNO3 and analyzed for its δ18O. Comparing with an original ion exchange technique, the benefits of improved method are: (1) the procedure employed to separate nitrate reduced from 5 steps to 3 steps; (2) the time taken to sample preparation dropped from 3~5 days to 1-2 days; (3) reduction of the need for expensive chemical reagents; (4) reduction of oxygen isotopic fractionation. [ABSTRACT FROM AUTHOR]

The Agulhas Current (AC) had been quite variable during the Quaternary Period, which not only impacted the Agulhas Leakage (AL) but also caused changes in the AMOC. To study the changes in the strength of AC, planktic foraminiferal census count and stable oxygen isotope data from the IODP Hole U-1474A were generated for the last 1.2 million years (My). We recorded significant variations in the abundance of climate-sensitive species, which were grouped according to their ecological preference as warm tropical-subtropical Agulhas Fauna (AF), temperate-subpolar Southern Ocean Fauna (SOF), stable oxygen isotope records and the Subtropical Front (STF) Index. The correlation of these records suggests that the strength of AC reduced during seven intervals during the last 1.2 My, in response to cooling climate, which led to the northward shift of STF. The studied interval was divided into three periods of MPT, MPT-MBE and post-MBE events. The AC was strongest after the Mid-Brunhes Event (0.43 Ma) as compared to the Mid-Pleistocene Transition (MPT) and post-MPT to MBE intervals. [ABSTRACT FROM AUTHOR]

Viticulture around the world is currently affected by climate change, which is causing an increasing scarcity of water resources necessary for the maintenance of vineyards. Despite the drought hardiness of grapevine (Vitis vinifera L.), this threat seriously compromises its cultivation in the near future, particularly in wine-growing areas with a semi-arid climate. Identifying varieties capable of producing suitable yields and good-quality grapes under drought conditions is integral to ensuring the sustainability of the wine sector. This study focuses on vines from both minority and widely grown varieties, which were supplied only with the water intended to ensure their survival. The carbon and oxygen isotope ratios, yield, and quality parameters were evaluated on the vines and musts during the period of 2018–2020. The results revealed that not all varieties responded equally well to drought. Albillo Real, Coloraillo, Macabeo, and Verdejo adapted well to drought conditions, simultaneously maintaining high yields and must quality. By contrast, Pedro Ximénez can be considered poorly adapted. This variety was the one that produced the lowest yield and had low acidity levels in the must. [ABSTRACT FROM AUTHOR]

Drought is perhaps the most important abiotic stressor affecting plants. Grapevine (Vitis vinifera L.) is a drought-tolerant species, and this feature makes it a traditional crop in semi-arid climate areas. However, not all cultivars respond to drought in the same way. Many studies on grapevine drought response have focused on physiological traits. This study mainly used agronomic indicators to assess the drought response of 13 red cultivars. Our results revealed high variability in must isotope ratios (δ13C and δ18O), yield components, and grape must quality. Bobal, Garnacha Peluda, Garnacha Tinta, Mazuela, and Moribel cultivars responded well to drought conditions, simultaneously maintaining high yields and must quality. By contrast, Garnacha Tintorera, Forcallat Tinta, and Tempranillo cultivars showed high water use efficiency but had low yield and must quality. Therefore, these cultivars can be considered poorly adapted to drought conditions. By knowing which cultivars perform well under drought conditions, viticulturists can reduce their reliance on water irrigation and continue to maintain vineyard sustainability in current and future semi-arid climatic conditions. This research also contributes novel information about the Castilla-La Mancha region, where there have been no previous similar assays. [ABSTRACT FROM AUTHOR]

Abstract In the East Asian monsoon area, stalagmites generally record lower and higher oxygen isotope (δ18O) levels during warm humid interglacial and cold dry glacial periods, respectively. Here, we report unusually low stalagmite δ18O from the last glacial period (ca. 32.2–22.3 ka) in Fukugaguchi Cave, Niigata Prefecture, Japan, where a major moisture source is the East Asian winter monsoon (EAWM) that carries vapor from the warm surface of the Japan Sea. The δ18O profile of this stalagmite may imply millennial-scale changes, and high δ18O intervals that are related to Dansgaard–Oeschger (D–O) interstadials. More importantly, the stalagmite exhibits low overall δ18O values; the mean δ18O (− 8.87‰) is distinctly lower than the mid-Holocene mean of another stalagmite from the same cave (4.2–8.2 ka, − 7.64‰). An interpretation assuming a more intense EAWM and greater vapor transportation during the last glacial period, compared with the mid-Holocene, contradicts the limited inflow of the Tsushima Warm Current into the Japan Sea because of lowered sea level. Additionally, our model calculation using δ18O data from meteoric water indicated that the amount effect of winter meteoric water was insignificant (1.2‰/1000 mm). Low stalagmite δ18O for the last glacial period in Fukugaguchi Cave most likely resulted from 18O-depleted surface water, which developed in the isolated Japan Sea. The estimated amplitude of the δ18O decrease in surface water was ~ 3‰ at most, consistent with the abnormally low values for foraminifera (by ~ 2.5‰) in sediment during the last glacial period, shown by samples collected from the Japan Sea. This is the first terrestrial evidence of 18O depletion in Japan Sea surface water during the last glacial period.

Viticulture around the world is currently affected by climate change, which is causing an increasing scarcity of water resources necessary for the maintenance of vineyards. Despite the drought hardiness of grapevine (Vitis vinifera L.), this threat seriously compromises its cultivation in the near future, particularly in wine-growing areas with a semi-arid climate. Identifying varieties capable of producing suitable yields and good-quality grapes under drought conditions is integral to ensuring the sustainability of the wine sector. This study focuses on vines from both minority and widely grown varieties, which were supplied only with the water intended to ensure their survival. The carbon and oxygen isotope ratios, yield, and quality parameters were evaluated on the vines and musts during the period of 2018–2020. The results revealed that not all varieties responded equally well to drought. Albillo Real, Coloraillo, Macabeo, and Verdejo adapted well to drought conditions, simultaneously maintaining high yields and must quality. By contrast, Pedro Ximénez can be considered poorly adapted. This variety was the one that produced the lowest yield and had low acidity levels in the must.

Drought is perhaps the most important abiotic stressor affecting plants. Grapevine (Vitis vinifera L.) is a drought-tolerant species, and this feature makes it a traditional crop in semi-arid climate areas. However, not all cultivars respond to drought in the same way. Many studies on grapevine drought response have focused on physiological traits. This study mainly used agronomic indicators to assess the drought response of 13 red cultivars. Our results revealed high variability in must isotope ratios (δ13C and δ18O), yield components, and grape must quality. Bobal, Garnacha Peluda, Garnacha Tinta, Mazuela, and Moribel cultivars responded well to drought conditions, simultaneously maintaining high yields and must quality. By contrast, Garnacha Tintorera, Forcallat Tinta, and Tempranillo cultivars showed high water use efficiency but had low yield and must quality. Therefore, these cultivars can be considered poorly adapted to drought conditions. By knowing which cultivars perform well under drought conditions, viticulturists can reduce their reliance on water irrigation and continue to maintain vineyard sustainability in current and future semi-arid climatic conditions. This research also contributes novel information about the Castilla-La Mancha region, where there have been no previous similar assays.

In the East Asian monsoon area, stalagmites generally record lower and higher oxygen isotope (δ18O) levels during warm humid interglacial and cold dry glacial periods, respectively. Here, we report unusually low stalagmite δ18O from the last glacial period (ca. 32.2–22.3 ka) in Fukugaguchi Cave, Niigata Prefecture, Japan, where a major moisture source is the East Asian winter monsoon (EAWM) that carries vapor from the warm surface of the Japan Sea. The δ18O profile of this stalagmite may imply millennial-scale changes, and high δ18O intervals that are related to Dansgaard–Oeschger (D–O) interstadials. More importantly, the stalagmite exhibits low overall δ18O values; the mean δ18O (− 8.87‰) is distinctly lower than the mid-Holocene mean of another stalagmite from the same cave (4.2–8.2 ka, − 7.64‰). An interpretation assuming a more intense EAWM and greater vapor transportation during the last glacial period, compared with the mid-Holocene, contradicts the limited inflow of the Tsushima Warm Current into the Japan Sea because of lowered sea level. Additionally, our model calculation using δ18O data from meteoric water indicated that the amount effect of winter meteoric water was insignificant (1.2‰/1000 mm). Low stalagmite δ18O for the last glacial period in Fukugaguchi Cave most likely resulted from 18O-depleted surface water, which developed in the isolated Japan Sea. The estimated amplitude of the δ18O decrease in surface water was ~ 3‰ at most, consistent with the abnormally low values for foraminifera (by ~ 2.5‰) in sediment during the last glacial period, shown by samples collected from the Japan Sea. This is the first terrestrial evidence of 18O depletion in Japan Sea surface water during the last glacial period. [ABSTRACT FROM AUTHOR]

For this study, to elucidate the East Asian monsoon variations on seasonal, interannual, and decadal timescales during the Late Holocene, we generated a 237-year-long time series of bimonthly resolved oxygen isotope ratios (δ18O) from a 3.5–3.2 ka Porites coral in Kikai Island, southwestern Japan. The coral data clearly show seasonal-to-interdecadal variations reflecting seawater temperature and salinity variations for 237 years, which can be a robust benchmark with respect to subtropical Pacific climate variability during the Late Holocene. Along with modern and fossil coral records published earlier from Kikai Island and Okinawa Island, the time-weighted δ18O averages for overlapped 14C ages demonstrate that the annual and summer values had slightly increased by <0.2‰ for 6–3 ka and that the winter values had increased by ∼0.2‰ for 6–5 ka and decreased by ∼0.2‰ for 5–3 ka. The result indicates that the mean climate state around the island had been almost stable on a centennial-to-millennium timescale throughout the transition from the Middle to Late Holocene, but with several short-term cooling excursions of ∼1 °C at 4–3 ka. On interdecadal-to-interannual timescales, amplitudes of the fossil coral δ18O variations for winter and summer were similar or larger at 3.5–3.2 ka relative to today, revealing significant periodicities at 36–38 years, 20–21 years, 6–9 years, and 3–4 years by spectral analysis at 95% confidence intervals. Furthermore, winter and summer coral δ18O time series of the respective periodic components indicate that interannual variations of SST (and/or seawater δ18O) around the island have changed on interdecadal and decadal timescales, which have been modulated on a multidecadal timescale of approximately 60–90 years/cycle. These results imply that the relationships of the East Asian winter and summer monsoon to the El Niño/Southern Oscillation and Pacific Decadal Oscillation dominant in the North Pacific might have been modulated by or associated with the Atlantic Multidecadal Oscillation dominant in the North Atlantic during the Late Holocene. • The longest bimonthly resolved δ18O time series for 237 years of all reported fossil coral records to date was generated. • The mean climate state in the Ryukyu Islands was stable on a centennial-to-millennium timescale at 5–3 ka with occasional ∼1 °C coolings at 4–3 ka. • On interannual-to-interdecadal timescales, seawater temperature and salinity variations were pronounced at 3.5–3.2 ka relative to today. • Relation of the East Asian monsoon to interannual-to-decadal climate variations was modulated on a multidecadal timescale during the Late Holocene. [ABSTRACT FROM AUTHOR]

Rutile occur in important amounts within Quaternary detrital sediments, and quartz veins which cut down the Paleozoic aged Eşme formation in the Menderes Massif on the Neoproterozoic Pan-Afrikan Belt in the west of Turkey. As a result of erosion, transport and accumulation of rutile-bearing quartz veins in the mica schists of the Eşme formation outcropped between Eşme (Uşak) and Kula (Manisa), the placer rutile occurrences occur in terraces, fluvial-alluvial and eluvial deposits. This study investigates the element content of rutile, oxygen isotope ratios of rutile and quartz, and formation temperature of rutile related to titanium source rock. Field observations show that rutiles are located in quartz veins that cut the schists. After these veins were fragmented and eroded, blocks of quartz with rutile and rutile grains are transported into clastic sediments in slope debris (eluvial), terraces and recent fluvial-alluvial deposits. Whereas quartz, rutile, ilmenite, and albite are found in the paragenesis of the rutile-bearing quartz vein fragments, the placers forming the terraces and current fluvial-alluvial deposits contain quartz, albite, muscovite, orthoclase, kaolinite, rutile, dravite, ilmenite, and zircon. The rutile grains in the examined placers and quartz vein fragments have grain sizes ranging from mm fractions to 5–6 cm. The major oxide compositions of the rutile grains have average values of 94 wt.% TiO 2 , 1.5 wt.% Fe 2 O 3 , 0.5 wt.% SiO 2 , and 0.3 wt.% Al 2 O 3 . The rutile samples have average values Nb of 1424 ppm, V of 980 ppm, W of 192 ppm, Ta of 94 ppm, and Zr of 73 ppm. The rutiles in the study area are defined as iron-rich rutile “nigrine” due to high iron content. Quartz veins are host rocks of rutile grains in the terrace and fluvial-aluvial sediments. The rutile-bearing quartz veins may be sourced from the Lower-Middle Miocene aged granites which are intruded the rocks in the Menderes Massif. Based on the analysis results of the methods of Zr thermometer from Zr values containing rutile and quartz-rutile geothermometer from oxygen isotope results (13.5‰ and 6‰) of quartz and rutile samples, the formation temperature of the rutile-bearing quartz veins were found to be at temperatures of 537 °C and 561 °C, respectively. These temperatures indicate that the rutile-bearing quartz veins may be in a temperature range between pegmatitic and/or hydrothermal stages. [ABSTRACT FROM AUTHOR]

Abstract: To validate the usability of the giant clam shell as a recorder of short‐term environmental changes such as typhoons, we collected a live Tridacna maxima from Okinotori Island, Japan, on 15 June 2006. Growth increment thickness, stable isotope ratio (δ18Oshell, δ13Cshell), and the barium/calcium ratio (Ba/Ca) in the T. maxima shell sample were measured and compared to Okinotori Island instrumental environmental data. In the outer layer of the shell sample, there were 365 ± 6 growth increments per year, as estimated by the δ18Oshell profile compared with sea surface temperature. The growth increments in the specimen were formed daily, and thus, we can determine the date of the sampling points of δ18Oshell, δ13Cshell and the Ba/Ca ratio by counting growth increments. After typhoon approach, there is a decrease in increment thickness and some disturbed growth increments. The positive peaks in the shell Ba/Ca ratio and δ18Oshell corresponded to lower sea surface temperature caused by typhoons. These results indicated that the microstructural and geochemical record in Tridacna maxima shells could be useful for detecting past typhoon events. [ABSTRACT FROM AUTHOR]

To clarify the time evolution of water origins in the vicinity of a tropical cyclone (TC)'s center, we have simulated Typhoon Man-yi (July 2007) in our case study, using an isotopic regional spectral model. The model results confirm that the replacement of water origins occurs successively as the TC develops and migrates northward over the western North Pacific. It is confirmed that, in this case, a significant proportion of total precipitable water around the cyclone center comes from external regions rather than the underlying ocean during the mature stage of a TC. Similar features can also be seen in the proportion of each oceanic origin to total condensation. Indian Ocean, South China Sea, and Maritime Continent water vapors begin to increase gradually at the developing stage and reach their peak at the decay stage when the TC approaches southwestern Japan. These remote ocean vapors are transported to the east of the cyclone via the moisture conveyor belt, a zone characterized by distinct low-level moisture flux that stretches from the Indian Ocean to the TC, and are further supplied into the inner region of the TC by inflow within the boundary layer associated with its secondary circulation. Since it takes time to undergo these two dynamic processes, the delayed influence of remote ocean vapors on the TC appears to become evident during the mature stage. [ABSTRACT FROM AUTHOR]

• Background and Aims Despite the importance of growth [CO2] and water availability for tree growth and survival, little information is available on how the interplay of these two factors can shape intraspecific patterns of functional variation in tree species, particularly for conifers. The main objective of the study was to test whether the range of realized drought tolerance within the species can be affected by elevated [CO2]. • Methods Intraspecific variability in leaf gas exchange, growth rate and other leaf functional traits were studied in clones of maritime pine. A factorial experiment including water availability, growth [CO2] and four different genotypes was conducted in growth rooms. A 'water deficit' treatment was imposed by applying a cycle of progressive soil water depletion and recovery at two levels of growth [CO2]: 'ambient [CO2]' (aCO2 400 μmol mol-1) and 'elevated [CO2]' (eCO2 800 μmol mol-1). • Key Results eCO2 had a neutral effect on the impact of drought on growth and leaf gas exchange of the most drought-sensitive genotypes while it aggravated the impact of drought on the most drought-tolerant genotypes at aCO2. Thus, eCO2 attenuated genotypic differences in drought tolerance as compared with those observed at aCO2. Genotypic variation at both levels of growth [CO2] was found in specific leaf area and leaf nitrogen content but not in other physiological leaf traits such as intrinsic water use efficiency and leaf osmotic potential. eCO2 increased Δ13C but had no significant effect on δ18O. This effect did not interact with the impact of drought, which increased δ18O and decreased Δ13C. Nevertheless, correlations between Δ13C and δ18O indicated the non-stomatal component of water use efficiency in this species can be particularly sensitive to drought. • Conclusions Evidence from this study suggests elevated [CO2] can modify current ranges of drought tolerance within tree species. [ABSTRACT FROM AUTHOR]

• Background and Aims Despite the importance of growth [CO2] and water availability for tree growth and survival, little information is available on how the interplay of these two factors can shape intraspecific patterns of functional variation in tree species, particularly for conifers. The main objective of the study was to test whether the range of realized drought tolerance within the species can be affected by elevated [CO2]. • Methods Intraspecific variability in leaf gas exchange, growth rate and other leaf functional traits were studied in clones of maritime pine. A factorial experiment including water availability, growth [CO2] and four different genotypes was conducted in growth rooms. A 'water deficit' treatment was imposed by applying a cycle of progressive soil water depletion and recovery at two levels of growth [CO2]: 'ambient [CO2]' (aCO2 400 μmol mol-1) and 'elevated [CO2]' (eCO2 800 μmol mol-1). • Key Results eCO2 had a neutral effect on the impact of drought on growth and leaf gas exchange of the most drought-sensitive genotypes while it aggravated the impact of drought on the most drought-tolerant genotypes at aCO2. Thus, eCO2 attenuated genotypic differences in drought tolerance as compared with those observed at aCO2. Genotypic variation at both levels of growth [CO2] was found in specific leaf area and leaf nitrogen content but not in other physiological leaf traits such as intrinsic water use efficiency and leaf osmotic potential. eCO2 increased Δ13C but had no significant effect on δ18O. This effect did not interact with the impact of drought, which increased δ18O and decreased Δ13C. Nevertheless, correlations between Δ13C and δ18O indicated the non-stomatal component of water use efficiency in this species can be particularly sensitive to drought. • Conclusions Evidence from this study suggests elevated [CO2] can modify current ranges of drought tolerance within tree species. [ABSTRACT FROM AUTHOR]

We undertook an environmental isotope investigation of groundwater from the Turonian Aquifer of Tadla Basin in Morocco in order to confirm that this aquifer could be a potential site for palaeoclimate reconstruction. The collected groundwater samples were examined for stable oxygen, hydrogen and carbon isotope ratio, as well as noble gases (He, Ne, Ar, Kr, Xe), 14 C and 3 H concentration. The measured stable oxygen and hydrogen isotope values show that the Turonian aquifer has two recharge areas, one with a heavier isotopic signature from the unconfined aquifer in the northern region (the area of Boujad), while the other is characterised by lighter isotopic composition in the north-eastern to the south-western part of the basin (to the North from Kasba Tadla). The calculated noble-gas solubility temperatures of the confined part of the aquifer are 2 °C higher than the recent mean annual air temperature (19 °C). Radiocarbon ages obtained from running different versions of Ingerson-Pearson models indicated that the recharge of this water occurred during the Holocene. We conclude that the Turonian aquifer might be a potential place for Late-Pleistocene palaeoclimate reconstruction if the research area were extended in the direct of flow path towards the western part of the basin and towards the foothills of the Phosphates Plateau. [ABSTRACT FROM AUTHOR]

Clinopyroxene and amphibole are the main mafic minerals in peralkaline granites of the Papanduva Pluton, Morro Redondo Complex, one of the most important granitic occurrences within the Graciosa A-type Province, S-SE Brazil. Clinopyroxene is present as three distinct late- to post-magmatic textural generations of aegirine, as well as post-magmatic aegirine–augite. Amphibole is predominantly magmatic ferrorichterite and arfvedsonite, and post-magmatic riebeckite. Major and trace element compositions reveal evolutionary trends characterized by increasing Fe 3 + and Na and decreasing Fe 2 + , Ca, HFSE, and REE contents from core to crystal rims; trace element and REE partitioning is controlled by the composition of the coexisting melts or fluid phases, as well as by crystal chemistry. δ 18 O values for minerals investigated range from + 2.3 to + 6.4‰ and correlate both with increasing degrees of alkalinity and quasi-solidus (sub-magmatic) deformation affecting several granites of the Papanduva Pluton. These deformation events played a significant role in the concentration and circulation of residual melts and fluid phases from which amphiboles and clinopyroxenes precipitated. Combined textural, chemical, and O isotope findings suggest that these fluids evolved through more oxidizing (close to the FMQ buffer), alkali- (i.e. peralkaline), fluorine-, and 18 O-rich conditions, associated with higher abundances of HFSEs and REEs within a temperature interval between 750 and 700 °C (late-magmatic stages) and 400–450 °C (post-magmatic stages). [ABSTRACT FROM AUTHOR]

There is much debate regarding the temporal and spatial pattern of hydroclimate variations on the Tibetan Plateau during the Holocene, focusing especially on the dipolar pattern of precipitation and moisture between the southern and northern regions, on multiple timescales. Modern observations reveal that the δ18O in precipitation is an integrated tracer of the atmospheric processes of the Indian summer monsoon (ISM), the East Asian summer monsoon (EASM), and the westerlies, which dominate the climate of the Tibetan Plateau. Here, we summarize and compare 20 Holocene lacustrine authigenic carbonate δ18O records from lakes distributed across the Tibetan Plateau. After carefully considering the potential effects of temperature, evaporation, site elevation, meltwater supply, and moisture sources, we eliminate their influences on the isotopic composition of Tibetan lakes, and suggest that the long-term variations of the lacustrine δ18O records were dominated by the moisture sources. The δ18O values of the lake sediments in the central and western Tibetan Plateau increased since the early Holocene, which agrees with the trend of δ18O in speleothem records from the plateau, as well as with the variations of monsoon precipitation reconstructions for the region. Overall, this evidence indicates the substantial influence of the monsoon in the abovementioned regions. However, the δ18O records from lakes in the northeastern Tibetan Plateau show a decreasing trend during the second half of the Holocene (after ∼5 ka), highlighting the operation of a different hydrological process, with enhanced moisture availability, in the regions. It has been suggested that the increased contribution from westerlies-derived moisture in the non-monsoon season, with depleted δ18O (e.g., from melting snow or frozen soil in spring), is responsible for such variations. We propose that the interplay between the Asian summer monsoon and the westerlies was the major control of the hydroclimatic variations on the Tibetan Plateau during the Holocene, which led to the dipolar pattern of moisture variation between the northeastern Tibetan Plateau and other parts of the plateau, on the multi-millennial timescales during the Holocene. [ABSTRACT FROM AUTHOR]

Past sea surface temperature (SST) and salinity (SSS) changes in the northeastern East Sea/Japan Sea since 19 cal ka BP have been reconstructed by using an alkenone unsaturation index and the oxygen isotope ratio of planktonic foraminifera Neogloboquadrina pachyderma (s) in Core MR0604-PC03B. Coretop alkenone temperature and calcification temperature correspond to the temperature of seawater in summer and spring at the depth of 10–30 m, respectively. Based on the records from this core and previous studies, spatio-temporal changes in alkenone temperature of the East Sea/Japan Sea have been reconstructed to investigate changes of surface circulations and the subpolar front (SPF) position. During the transitional period from the glacial to the Holocene, the SST was lower (about 2–3 °C) than that of today and the SSS dramatically increased at that time in the entire East Sea/Japan Sea but it was still lower than that of today. However, the northern SSS was higher than that of the southern part. The source of the cold and saline seawater could have been the Oyashio Current (OY, inflow from the north), not the Tsushima Warm Current (TWC, inflow from the south). Probably, sea level rose rapidly at that time. There might be no strong development of the SPF during the transitional period due to the restricted inflow of the TWC. During the early Holocene, the SST and SSS of the East Sea/Japan Sea increased compared to the transitional period due to increased seawater exchange through straits. The SPF was tilted orienting from southwest to northeast because the inflow of the TWC was not fully developed due to lower sea level. Subsequently, the surface condition of the East Sea/Japan Sea was similar to that of today at 6 cal ka BP. The Forerunner of Soya Warm Water (FSWW) that flowed out through the Soya Strait in early spring did not affect the formation of the Okhotsk Sea Intermediate Water and the North Pacific Intermediate Water during the glacial and interglacial periods. [ABSTRACT FROM AUTHOR]

ABSTRACT We present a method for determining sub-milligram quantities of biogenic opal. The method employs the inductive high-temperature carbon reduction method for dehydration of opal and reduction of silica, and a continuous-flow isotope ratio mass spectrometry system for direct analysis of the oxygen isotope ratio in the evolved carbon monoxide. The accuracy and precision of the online analytical system were evaluated by isotopic analysis of various quantities of standard SiO2 in the range 40-538 µg. The time required to analyse a single sample was relatively short (50 min); hence, our method is suitable for routine analysis for paleoenvironmental studies that require large amounts of time-series data. The method was validated for samples in the sub-milligram range and can be applied to oxygen isotope analysis of various types of biogenic opal that have not been analysed because of their small amounts in natural samples. We successfully applied our method to (i) the first oxygen isotope analysis of monospecific radiolarian skeletons and (ii) high-resolution oxygen isotope analysis of Holocene diatom frustules from the Southern Ocean. [ABSTRACT FROM AUTHOR]

Abstract: As application of coral-based climate reconstruction has become more frequent at tropical sites, increased attention is being paid to the potential ambiguities of coral thermometers that are intrinsic to the biomineralisation process, including the so-called vital effect, the growth-rate-related kinetic effect, and the [CO3 2−] effect. Here we studied how the growth rate influenced the skeletal oxygen and carbon isotope ratios (δ 18O and δ 13C) and the Sr/Ca ratio in a common-garden experiment involving the long-term culture of Porites australiensis clone colonies. Comparison of the seasonal minimum δ 18O values during summer showed a negligible influence of the large intercolony variation in growth rate (2–10mmyr−1) on δ 18O variation, but δ 18O was relatively sensitive to temporary intracolony growth-rate changes related to colony health. In contrast, the Sr/Ca ratio was robust against both inter- and intracolony growth-rate variation. We found a positive shift in δ 13C in slower growing corals, which we attributed to the kinetic behaviour of the calcification reaction. The seasonal fluctuation in δ 13C corresponded not to changes in light intensity nor to δ 13C of dissolved inorganic carbon in seawater, but to photosynthetic efficiency as measured by pulse-amplitude photometry. These findings support the inference that coral skeletal Sr/Ca and δ 18O in a long-lived colony can function as a palaeoclimate archive by recording signals of clonal growth. We also propose practical guidelines for the proper interpretation of coral records. [Copyright &y& Elsevier]

Abstract: In-situ analyses for oxygen isotope ratio and trace element concentration by ion microprobe of 3.3–3.7Ga zircons from rhyolite of Panorama Formation in the North Pole Dome, Pilbara Craton document intracrystalline patterns of variability, show compositional correlation, and provide metrics to assess alteration. Values of δ18O in the North Pole Dome (NPD) zircons average 5.78 ‰ with a tight range from 5.3 to 6.4 ‰ VSMOW. These values are similar to magmatic zircons throughout the Archean worldwide and there is no correlation of δ18O, Ur trace elements. SEM/CL examination shows no evidence of mineral inclusions in the SIMS analysis pits. In-situ analysis of Ca concentration is useful to assess the degree of alteration in zircon and retention of trace element compositions. Most zircon analyses (74 %) have elevated [Ca]≥120ppm, with values up to 1614ppm suggesting alteration, probably facilitated by radiation damage. Many high-Ca zircons show enrichment in middle–heavy REE (M–HREE), a peak near Dy, and concave-down trends in chondrite-normalized diagrams. The calculated Dy anomalies (Dy/Dy*) correlate with [Ca]. High Ca also correlates with P, Ti, Fe, Y and REE, and with cumulative (unannealed) α-doses from radiactive decay of Th and U (3.1 to 20×1015 events/mg). If not annealed, this α-dose could have caused radiation damage that exceeded the first percolation point. Radiation damage can also facilitate alteration of δ18O in zircon, but examples from other terranes show that alteration is heterogeneous and correlates to greater variability of δ18O within and among zircons. The tight range of oxygen isotope ratios in the NPD rhyolite zircons and their similarity to other Archean zircons, world-wide, suggests that the analyzed NPD zircons have retained original, magmatic oxygen isotope ratios. [Copyright &y& Elsevier]

Abstract: Over exploitation of fish stocks in coastal areas is a subject of global concern. Increasing numbers of traditional fish traps, recreational fishing effort and unknown extents of illegal gillnetting are blamed for the declining abundance of estuarine-dependent fish species in the Kosi Bay estuarine lake system in KwaZulu-Natal, South Africa. Otoliths from four important fishery species (Lutjanus argentimaculatus, Pomadasys commersonnii, Acanthopagrus vagus, and Rhabdosargus sarba) and water samples collected from throughout the Kosi Bay system were analyzed for trace element constituents and δ 18O values, in an attempt to reconstruct fish movements. The applied microscopic X-ray fluorescence analysis proved valuable in detecting μm-scale spatially resolved Sr/Ca ratio distributions across otolith thin sections. Sr/Ca ratios and δ 18O in otoliths correlated well with ambient water conditions and, thus, enabled us to reconstruct migratory histories of individual fish in the estuarine lake system. The findings are representative of the known biology of these species, although exact spatial and temporal ranges of migrations remain unclear. Interestingly, samples of two species (L. argentimaculatus and R. sarba) did not show any clue of migrations back to sea, which would be necessary for successful spawning. Further laboratory and field investigations with larger sample sizes are necessary to detect fishery impacts on migratory behavior at a population level. [Copyright &y& Elsevier]

Beaudon, E., Arppe, L., Jonsell, U., Martma, T., Möller, M., Pohjola, V.A., Scherer, D. and Moore, J.C., 2011. Spatial and temporal variability of net accumulation from shallow cores from Vestfonna ice cap (Nordaustlandet, Svalbard). Geografiska Annaler: Series A, Physical Geography, 93, 287-299. DOI: 10.1111/j.1468-0459.2011.00439.x Abstract We analyse ice cores from Vestfonna ice cap (Nordaustlandet, Svalbard). Oxygen isotopic measurements were made on three firn cores (6.0, 11.0 and 15.5 m deep) from the two highest summits of the glacier located on the SW-NE and NW-SE central ridges. Sub-annual δ18O cycles were preserved and could be counted visually in the uppermost parts of the cores, but deeper layers were affected by post-depositional smoothing. A pronounced δ18O minimum was found near the bottom of the three cores. We consider candidates for this δ18O signal to be a valuable reference horizon since it is also seen elsewhere in Nordaustlandet. We attribute it to isotopically depleted snow precipitation, which NCEP/NCAR reanalysis shows was unusual for Vestfonna, and came from northerly air during the cold winter of 1994/95. Finding the 1994/95 time marker allows establishment of a precise depth/age scale for the three cores. The derived annual accumulation rates indirectly fill a geographical gap in mass balance measurements and thus provide information on spatial and temporal variability of precipitation over the glacier for the period spanned by the cores (1992-2009). Comparing records at the two locations also reveals that the snow net accumulation at the easternmost part of Vestfonna was only half of that in the western part over the last 17 years. [ABSTRACT FROM AUTHOR]

Abstract: Distributions of sea-ice melt (SIM) and runoff (RW) were determined in Hudson Bay (Canada) using salinity and oxygen isotope (δ18O) tracers. In late summer/early fall, stations throughout the Bay exhibited a summer surface mixed layer (SSML) 30–60m deep, which contained the seasonal freshwater inputs. The SSML overlies a cold subsurface water, extending up to 125m deep in the water column, indicative of the previous winter''s surface mixed layer (WSML). Our data show that most of the RW remains in a nearshore coastal regime in summer, with limited exchange into the interior of the Bay. At depth, brine (negative SIM) accumulation is closely associated with excess RW, implying that deep water formation occurs when sufficient brine is rejected from the growing ice to overcome RW buoyancy in surface water. The inventory of RW at depths below the WSML is equivalent to almost one year''s runoff inputs which, given a residence time of deep water of 4–14years, implies that 6–16% of the annual river discharge is shunted into deeper waters each winter. The balance between the RW buoyancy in surface waters and densification due to ice formation appears to control where and when deep-water formation can occur. Although not directly measured, regions forming deep water are likely small (<10% of the Bay area) and associated with flaw leads extending around the perimeter of the landfast ice edge in the Bay. The processes evident in δ18O and salinity data must be incorporated into ocean models to obtain a realistic view of freshwater cycling and its sensitivity to climate perturbations. [Copyright &y& Elsevier]

Measurements of δ(13C) determined on CO2 with an isotope-ratio mass spectro m - eter (IRMS) must be corrected for the amount of 17O in the CO2. For data consistency, this must be done using identical methods by different laboratories. This report aims at unifying data treatment for CO2 IRMS by proposing (i) a unified set of numerical values, and (ii) a unified correction algorithm, based on a simple, linear approximation formula. Because the oxygen of natural CO2 is derived mostly from the global water pool, it is recommended that a value of 0.528 be employed for the factor λ, which relates differences in 17O and 18O abundances. With the currently accepted N(13C)/N(12C) of 0.011180(28) in VPDB (Vienna Peedee belemnite) reevaluation of data yields a value of 0.000 393(1) for the oxygen isotope ratio N(17O)/N(16O) of the evolved CO2. The ratio of these quantities, a ratio of isotope ratios, is essential for the 17O abundance correction: [N(17O)/N(16O)]/[N(13C)/N(12C)] = 0.035 16(8). The equation [δ(13C) ≈ 45δVPDB-CO2 + 2 17R/13R (45δVPDB-CO2 - λ46δVPDB-CO2)] closely approximates δ(13C) values with less than 0.010 ‰ deviation for normal oxygenbearing materials and no more than 0.026 ‰ in extreme cases. Other materials containing oxygen of non-mass-dependent isotope composition require a more specific data treatment. A similar linear approximation is also suggested for δ(18O). The linear approximations are easy to implement in a data spreadsheet, and also help in generating a simplified uncertainty budget. [ABSTRACT FROM AUTHOR]

We present oxygen and carbon isotope ratios and the morphological structure of the cultured freshwater pearl mussel ( Hyriopsis sp., Unionidae) shell and pearl. The number of first-order fluctuations of δ18O of the outer shell layer along the maximum growth axis was consistent with the number of cultured years. The dominant factor controlling annual δ18O fluctuations was water temperature with a minor contribution from the variation in δ18O of ambient water, especially during the rainy season. The δ13C values were approximately constant throughout the life of the mussel, suggesting that the contributions of body size to δ13C of the shell were minor. We observed nine distinct disturbance rings on the outer surface of the shell. Five rings coincided with the five winter peaks of the δ18O profile, indicating winter growth cessation below approximately 10°C, probably because of either inactive growth at low water temperatures or reproduction. Summer disturbance rings were not observed in all years. Moreover, some summer rings showed discontinuity in the inner structure. These findings suggest that summer growth cessation may be caused by occasional events such as heavy rains, as the decrease of dissolved oxygen concentration. The δ18O profile and shell structures indicated that shell aragonite was precipitated at close to equilibrium conditions with respect to the oxygen isotope composition of the ambient water. Hyriopsis sp. shells can potentially be used for reconstruction of past hydrologic conditions. The δ18O of a pearl indicated that calcification occurred over a temperature range of at least 13–23°C. The optimal temperature for pearl calcification in this species is lower than that for marine pearl calcification. [ABSTRACT FROM AUTHOR]

Water-use efficiency and stable isotope composition were studied in three tropical tree species. Seedlings of Tectona grandis, Swietenia macrophylla and Platymiscium pinnatum were grown at either high or low water supply, and with or without added fertilizer. These three species previously exhibited low, intermediate and high whole-plant water-use efficiency ( TE) when grown at high water supply in unfertilized soil. Responses of TE to water and nutrient availability varied among species. The TE was calculated as experiment-long dry matter production divided by cumulative water use. Species-specific offsets were observed in relationships between TE and whole-plant 13C discrimination (Δ13Cp). These offsets could be attributed to a breakdown in the relationship between Δ13Cp and the ratio of intercellular to ambient CO2 partial pressures ( ci/ ca) in P. pinnatum, and to variation among species in the leaf-to-air vapour pressure difference ( v). Thus, a plot of v· TE against ci/ ca showed a general relationship among species. Relationships between δ18O of stem dry matter and stomatal conductance ranged from strongly negative for S. macrophylla to no relationship for T. grandis. Results suggest inter-specific variation among tropical tree species in relationships between stable isotope ratios ( δ13C and δ18O) and the gas exchange processes thought to affect them. [ABSTRACT FROM AUTHOR]