Spatial variability of northern Iberian rainfall stable isotope values: Investigating climatic controls on daily and monthly timescales

Abstract. This article presents for the first time a large dataset of rainfall isotopic measurements (d18Op and d2Hp) sampled every day or every two days from seven sites in a west-to-east transect across northern Spain for 2010–2017. The main aim of this study is to: (1) characterize rainfall isotopic variability in northern Spain at daily and monthly time scales, and (2) assess the principal influencing factors determining rainfall isotopic variability. This comprehensive spatio-temporal approach allows exploring the role of air mass source in determining the isotopic composition of rainfall in northern Iberia by using back-trajectories; Atlantic fronts are found to be the dominant source of northern Iberia rain events studied. The relative role of air temperature and rainfall amount in determining the stable isotope composition of precipitation changes along the west-to-east transect. Air temperature appears to be the most significant influence on d18Op at daily and monthly time scales with the highest air temperature-d18Op dependency found for the Pyrenean station while a few sites in the transect show a significant negative correlation with precipitation amount. Distance from the coast, site elevation, and moisture source region (Atlantic versus Mediterranean) also significantly modulate the d18Op values and ranges but the type of precipitation (convective vs frontal rainfall) plays a key control, with convective rainfall associated with higher d18Op values. This dataset of the rainfall isotopic composition represents another step forward towards developing a more detailed, mechanistic framework for interpreting stable isotopes in rainfall as a palaeoclimate and hydrological tracer.

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Measurement report: Spatial variability of northern Iberian rainfall stable isotope values – investigating atmospheric controls on daily and monthly timescales

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-10159-2021 ◽

2021 ◽

Vol 21 (13) ◽

pp. 10159-10177

Author(s):

Ana Moreno ◽

Miguel Iglesias ◽

Cesar Azorin-Molina ◽

Carlos Pérez-Mejías ◽

Miguel Bartolomé ◽

...

Keyword(s):

Stable Isotope ◽

Isotopic Composition ◽

Air Temperature ◽

Isotope Composition ◽

Significant Negative Correlation ◽

Relative Role ◽

Northern Spain ◽

Mass Source ◽

Highly Correlated

Abstract. For the first time, this article presents a large dataset of precipitation isotopic measurements (δ18Op and δ2Hp) sampled every day or 2 d from seven sites on a west-to-east transect across northern Spain for 2010–2017. The main aim of this study is to (1) characterize the rainfall isotopic variability in northern Spain at daily and monthly timescales and (2) assess the principal factors influencing rainfall isotopic variability. The relative role of air temperature and rainfall in determining the stable isotope composition of precipitation changes along the west-to-east transect, with air temperature being highly correlated with δ18Op at daily and monthly timescales, while a few sites along the transect show a significant negative correlation with precipitation. The highest air temperature–δ18Op dependency is found for a station located in the Pyrenees. Frontal systems associated with North Atlantic cyclones are the dominant mechanism inducing precipitation in this region, particularly in winter. This study allows an exploration of the role of air mass source and trajectory in determining the isotopic composition of rainfall in northern Iberia by characterizing the moisture uptake for three of the seven stations. The importance of continental versus marine moisture sources is evident, with clear seasonal and spatial variations. In addition, the type of precipitation (convective versus frontal rainfall) plays a key role, with convective rainfall associated with higher δ18Op values. This comprehensive spatiotemporal approach to analyzing the rainfall isotopic composition represents another step forward towards developing a more detailed, mechanistic framework for interpreting stable isotopes in rainfall as a paleoclimate and hydrological tracer.

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Investigating late Holocene variations in hydroclimate and the stable isotope composition of precipitation using southern South American peatlands: an hypothesis

Climate of the Past ◽

10.5194/cp-8-1457-2012 ◽

2012 ◽

Vol 8 (5) ◽

pp. 1457-1471 ◽

Cited By ~ 12

Author(s):

T. J. Daley ◽

D. Mauquoy ◽

F. M. Chambers ◽

F. A. Street-Perrott ◽

P. D. M. Hughes ◽

...

Keyword(s):

Stable Isotope ◽

Air Temperature ◽

Regional Differences ◽

Late Holocene ◽

Isotope Composition ◽

Precipitation Amount ◽

Surface Air Temperature ◽

Global Network ◽

Stable Isotope Composition ◽

Δd And Δ18o

Abstract. Ombrotrophic raised peatlands provide an ideal archive for integrating late Holocene records of variations in hydroclimate and the estimated stable isotope composition of precipitation with recent instrumental measurements. Modern measurements of mean monthly surface air temperature, precipitation, and δD and δ18O-values in precipitation from the late twentieth and early twenty-first centuries provide a short but invaluable record with which to investigate modern relationships between these variables, thereby enabling improved interpretation of the peatland palaeodata. Stable isotope data from two stations in the Global Network for Isotopes in Precipitation (GNIP) from southern South America (Punta Arenas, Chile and Ushuaia, Argentina) were analysed for the period 1982 to 2008 and compared with longer-term meteorological data from the same locations (1890 to present and 1931 to present, respectively). δD and δ18O-values in precipitation have exhibited quite different trends in response to local surface air temperature and precipitation amount. At Punta Arenas, there has been a marked increase in the seasonal difference between summer and winter δ18O-values. A decline in the deuterium excess of summer precipitation at this station was associated with a general increase in relative humidity at 1000 mb over the surface of the Southeast Pacific Ocean, believed to be the major vapour source for the local precipitation. At Ushuaia, a fall in δ18O-values was associated with an increase in the mean annual amount of precipitation. Both records are consistent with a southward retraction and increase in zonal wind speed of the austral westerly wind belt. These regional differences, observed in response to a known driver, should be detectable in peatland sites close to the GNIP stations. Currently, insufficient data with suitable temporal resolution are available to test for these regional differences over the last 3000 yr. Existing peatland palaeoclimate data from two sites near Ushuaia, however, provide evidence for changes in the late Holocene that are consistent with the pattern observed in modern observations.

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Investigating late Holocene variations in hydroclimate and the stable isotope composition of precipitation using southern South American peatlands: a hypothesis

Climate of the Past Discussions ◽

10.5194/cpd-8-595-2012 ◽

2012 ◽

Vol 8 (1) ◽

pp. 595-620 ◽

Cited By ~ 4

Author(s):

T. J. Daley ◽

D. Mauquoy ◽

F. M. Chambers

Keyword(s):

Stable Isotope ◽

Air Temperature ◽

Regional Differences ◽

Late Holocene ◽

Isotope Composition ◽

Precipitation Amount ◽

Surface Air Temperature ◽

Tierra Del Fuego ◽

Stable Isotope Composition ◽

Δd And Δ18o

Abstract. Ombrotrophic raised peatlands provide an ideal archive for integrating late Holocene records of variations in hydroclimate and the estimated stable isotope composition of precipitation with recent instrumental measurements. Modern measurements of mean monthly surface air temperature, precipitation and δD and δ18O values in precipitation from the late twentieth and early twenty-first centuries provide a short but invaluable record with which to investigate modern relationships between these variables, thereby enabling improved interpretation of the peatland palaeodata. Data from two stations in the Global Network for Isotopes in Precipitation (GNIP) from Tierra del Fuego (Punta Arenas, Chile and Ushuaia, Argentina) were analysed for the period 1982 to 2008. In both locations, δD and δ18O values have decreased in response to quite different trends in local surface air temperature and total precipitation amount. At Ushuaia, the fall in δ18O values is associated with an increase in the mean annual amount of precipitation. At Punta Arenas, the fall in δ18O values is weakly associated with decrease in the precipitation amount and an increase in local temperatures. The pattern in both records is consistent with an increase in the zonal intensity of the southern westerly wind belt. These regional differences, observed in response to a known driver, should be detectable in peatland sites close to the GNIP stations. There is currently insufficient availability of suitably temporally resolved data to test for these regional differences over the last 3000 yr. Existing peatland palaeoclimate data from two sites near Ushuaia, however, provide evidence for changes in the late Holocene that are consistent with the pattern observed in modern observations. Furthermore, the records suggest synchroneity in millennial-scale oscillations between the Northern and Southern Hemispheres.

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Speleothem Stable Isotope Records from Eastern Europe & Turkey

10.20944/preprints201812.0038.v1 ◽

2018 ◽

Cited By ~ 2

Author(s):

Zoltán Kern ◽

Attila Demény ◽

István Gábor Hatvani

Keyword(s):

Stable Isotope ◽

Eastern Europe ◽

Oxygen Isotope ◽

Temporal Resolution ◽

Isotope Composition ◽

Precipitation Amount ◽

Temporal Distribution ◽

Elevation Gradients ◽

The Holocene ◽

Carbon And Oxygen Isotope

The region of Eastern Europe & Turkey contributed to the SISAL (Speleothem Isotopes Synthesis and AnaLysis) global database with stable carbon- and oxygen isotope time-series from 18 entities from 14 cave systems. The currently available oldest record from this region is the ABA-2 flowstone record (Abaliget Cave; Hungary) reaching back to MIS 6. The temporal distribution of the compiled 18 entities points out a ~20-kyr-long period, centering around 100 ka, lacking speleothem stable isotope record in the region. The regional subset of SISAL_v1 records displays a continuous coverage for the past ~90 kyr for both δ18O and δ13C, with a mean temporal resolution of ~12 yr for the Holocene, and >50 yr for the pre-Holocene period. The highest temporal resolution both for the Holocene and the pre-Holocene was achieved in the So-1 record (Sofular Cave; Turkey). Assessing the data, an important split was found regarding the climatic interpretation of speleothem δ18O. While the oxygen isotope composition of more continental formations is thought to reflect mainly temperature variations and changes in moisture transport trajectories, it may strongly reflect fluctuations of precipitation amount in the southern part of the region. Variations of δ13C primarily interpreted as humidity changes reflecting dry/wet periods across the region. Elevation gradients from three non-overlapping time periods from the region - for the last 5kyr - indicated systematically prevailing elevational gradients around -0.26&permil; 100m-1 in δ18O. The regional comparison of SISAL_v1 speleothem δ18O and the temporal distribution of coarsely crystalline cryogenic cave carbonate occurrences back to 45ka does not appear to confirm the finding that occurrence of the latter coincides with the warming from stadial to interstadial conditions.

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Barium stable isotopes as a fingerprint of biological cycling in the Amazon River basin

Biogeosciences ◽

10.5194/bg-17-5989-2020 ◽

2020 ◽

Vol 17 (23) ◽

pp. 5989-6015

Author(s):

Quentin Charbonnier ◽

Julien Bouchez ◽

Jérôme Gaillardet ◽

Éric Gayer

Keyword(s):

Organic Matter ◽

Stable Isotope ◽

Trace Element ◽

Isotope Composition ◽

Silicate Weathering ◽

Biological Cycling ◽

Biological Uptake ◽

Dissolved Load ◽

Silicate Rocks

Abstract. The biological cycle of rock-derived nutrients on the continents is a major component of element transfer between the Earth's surface compartments, but its magnitude currently remains elusive. The use of the stable isotope composition of rock-derived nutrients, which can be fractionated during biological uptake, provides a promising path forward with respect to quantifying biological cycling and its overall contribution to global element cycling. In this paper, we rely on the nutrient-like behaviour of the trace element barium (Ba) and use its elemental and stable isotope compositions in dissolved and sediment load river samples to investigate biological cycling in the Amazon Basin. From these measurements, we show that dissolved Ba mainly derives from silicate rocks, and a correlation between dissolved Ba and K abundances suggests that biological cycling plays a role in the Ba river budget. Furthermore, the isotope composition of Ba (δ138Ba) in the dissolved load was found to be significantly different from that of the parent silicate rocks, implying that dissolved Ba isotopic signatures are affected by (i) the precipitation of soil-forming secondary phases as well as (ii) biological uptake and release from dead organic matter. Results from an isotope mass balance method applied to the river dissolved load data indicate that, after its release to solution by rock weathering, Ba is partitioned between the river dissolved load, secondary weathering products (such as those found in soils and river sediments), and the biota. In most sub-catchments of the Amazon, river Ba abundances and isotope compositions are significantly affected by biological cycling. Relationships between estimates of Ba cycled through biota and independent metrics of ecosystem dynamics (such as gross primary production and terrestrial ecosystem respiration) allow us to discuss the role of environmental parameters such as climate or erosion rates on the biological cycling of Ba and, by extension, the role of major rock-derived nutrients. In addition, catchment-scale mass and isotope budgets of Ba show that the measured riverine export of Ba is lower than the estimated delivery of Ba to the Earth surface through rock alteration. This indicates the existence of a missing Ba component, which we attribute to the formation of Ba-bearing particulate organics (possibly accumulating as soil organic matter or currently growing biomass within the catchments) and to organic-bound Ba exported as “unsampled” river particulate organic matter. Given our findings on the trace element Ba, we explore whether the river fluxes of most major rock-derived nutrients (K, Mg, Ca) might also be significantly affected by biological uptake or release. A first-order correction of river-derived silicate weathering fluxes from biological cycling shows that the carbon dioxide (CO2) consumption by silicate weathering at the mouth of the Amazon could be several times higher than the previously reported value of 13 × 109 mol CO2 yr−1 (Gaillardet et al., 1997). Overall, our study clearly shows that the chemical and isotope compositions of rivers in the Amazon – and most likely in other large river basins – bear a biological imprint, thereby challenging common assumptions made in weathering studies.

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Isotopes of oxygen-18 and deuterium in precipitation in Slovakia / Izotopy kyslíka-18 A deutéria v zrážkach na Slovensku

Journal of Hydrology and Hydromechanics ◽

10.2478/v10098-012-0023-2 ◽

2012 ◽

Vol 60 (4) ◽

pp. 265-276 ◽

Cited By ~ 22

Author(s):

Ladislav Holko ◽

Michal Dóša ◽

Juraj Michalko ◽

Martin Šanda

Keyword(s):

Isotopic Composition ◽

Air Temperature ◽

Meteoric Water ◽

Precipitation Amount ◽

Data Series ◽

Water Line ◽

Temperature And Precipitation ◽

Meteoric Water Line ◽

The Mean ◽

Available Information

The article synthesizes available information on isotopic composition of precipitation in Slovakia (the Western Carpathians). Monthly δ18O data from eleven stations and period 1988-1997 were used to investigate correlations among the stations, altitude, air temperature and precipitation amount effects. The mean annual altitude and air temperature gradients of δ18O in precipitation were 0.21‰/100 m and 0.36‰/1°C, respectively. Maps of spatial distribution of mean annual δ18O in precipitation based on both gradients were constructed. The two maps do not significantly differ for the majority of Slovakia. δ2H data were available for only three stations. Local meteoric water line derived for the station with the longest data series (δ2H = = 7.86δ18O + 6.99) was close to the Global Meteoric Water line. Its parameters in periods 1991-1993 and 1991-2008 did not change. The study indicates that a more detailed monitoring of isotopic composition of precipitation in mountains should be carried out in the future. The highest station exhibited very small seasonal variability of δ18O in precipitation compared to other Slovak stations. The second highest mountain station had significantly higher deuterium excess than the neighboring stations located in the valley. In some analyses the data from the nearest stations situated abroad (Vienna, Krakow) were used.

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Chlorine stable isotope composition of granulites from Lofoten, Norway: Implications for the Cl isotopic composition and for the source of Cl enrichment in the lower crust

Earth and Planetary Science Letters ◽

10.1016/s0012-821x(97)00084-8 ◽

1997 ◽

Vol 150 (1-2) ◽

pp. 95-102 ◽

Cited By ~ 20

Author(s):

Gregor Markl ◽

Masaaki Musashi ◽

Kurt Bucher

Keyword(s):

Stable Isotope ◽

Isotopic Composition ◽

Lower Crust ◽

Isotope Composition ◽

Stable Isotope Composition ◽

Chlorine Stable Isotope

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The dominant environmental driver of leaf water stable isotope enrichment differs for H-2 compared to O-18

10.5194/egusphere-egu2020-3343 ◽

2020 ◽

Author(s):

Matthias Cuntz ◽

Lucas A Cernusak ◽

Keyword(s):

Stable Isotope ◽

Relative Humidity ◽

Air Temperature ◽

Gordon Equation ◽

Isotope Composition ◽

Environmental Variable ◽

Leaf Water ◽

Source Water ◽

Stable Isotope Composition ◽

Water Stable Isotope

Several important isotopic biomarkers derive at least part of their signal from the stable isotope composition of leaf water (e.g., leaf wax &#948;2H, cellulose &#948;2H and &#948;18O, lignin &#948;18O). In order to interpret these isotopic proxies, it is therefore helpful to know which environmental variable most strongly controls a given leaf water stable isotope signal. We collated observations of the stable isotope compositions of leaf water, xylem water, and atmospheric vapour, along with air temperature and relative humidity, to test whether the dominant driver of leaf water 2H concentration could differ from that of 18O concentration. Our dataset comprises 690 observations from 35 sites with broad geographical coverage. We limited our analysis to daytime observations, when the photosynthetic processes that incorporate the leaf water isotopic signal primarily take place. The Craig-Gordon equation was generally a good predictor for daytime bulk leaf water stable isotope composition for both &#948;2H (R2=0.86, p<0.001) and &#948;18O (R2=0.63, p<0.001). It showed about 10% admixture of source water was caused by unenriched water pools such as leaf veins or the P&#233;clet effect. Solving the Craig-Gordon equation requires knowledge of relative humidity, air temperature, and the stable isotope compositions of source water and atmospheric vapour. However, it is not possible to invert the Craig-Gordon equation to solve for one of these parameters unless the others are known. Here we show that the two isotopic signals of &#948;2H and &#948;18O are predominantly driven by different environmental variables: leaf water &#948;2H correlated most strongly with the &#948;2H of source water (R2=0.68, p<0.001) and atmospheric vapour (R2=0.63, p<0.001), whereas leaf water &#948;18O correlated most strongly with air relative humidity (R2=0.46, p<0.001). We conclude that these two isotopic signals of leaf water are not simply mirror images of the same environmental information, but carry distinct signals of different climate factors, with crucial implications for the interpretation of downstream isotopic biomarkers.

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