Science topic

Oxygen Isotopes - Science topic

Stable oxygen atoms that have the same atomic number as the element oxygen, but differ in atomic weight. O-17 and 18 are stable oxygen isotopes.
Questions related to Oxygen Isotopes
  • asked a question related to Oxygen Isotopes
Question
2 answers
I want to know the value of oxygen vacancies formation energy of Mn3O4. Please suggest some papers
Thanks
Relevant answer
Answer
Read this paper, I hope you will get your answer.
  • asked a question related to Oxygen Isotopes
Question
2 answers
Like carbon isotope from fossil tooth enamel, is oxygen isotope also have some specific values to define humid or arid areas?
Relevant answer
Answer
Oxygen Isotopes in Enamel Carbonate and their Ecological Significance
Matt Sponheimer
Journal of Archaeological Science (1999) 26, 723–728 Article No. jasc.1998.0388, available online at http://www.idealibrary.com
Our re-examination of the Swartkrans and Equus Cave data reveals several points of interest. First, enamel carbonate ä18O values have not been obscured by diagenesis. This is evident because taxa with diVerent eating/drinking behaviours remain isotopically discrete at both sites. Further, it is clear that drinking behaviour has a dominant eVect on mammalian oxygen isotope composition. In addition, these data suggest that diet, too, has a strong aVect on ä18O values inasmuch as it determines an animal’s drinking behaviour, and because diVerent food such as leaves, stems, and animal flesh are isotopically discrete. Together, these principles explain why some browsers are more enriched in 18O than grazers, while carnivores are depleted compared with herbivores.
  • asked a question related to Oxygen Isotopes
Question
2 answers
Dear colleagues,
I'm looking for a laboratory that measures clumped isotopes - Δ47. My research interests are carbonate minerals occurring in ultramafic rocks. I plan to reconstruct the formation conditions of various carbonates from ultramafic massifs from the north-east part of the Bohemian Massif. The carbonates were probably formed in both supergene and hydrothermal conditions and I aim to distinguish how these conditions had changed in terms of time and space. I would like to reconstruct magnesite precipitation conditions using clumped Isotope palaeothermometry.
Please let me know if you are open to collaboration and what are possible costs involved. Long-time scientific cooperation is possible :)
Contact me on Researchgate or blazej.cieslik2@uwr.edu.pl
Thanks!
Relevant answer
Answer
Hi! There is a clumped lab in ATOMKI, Debrecen, Hungary. Check it out.
  • asked a question related to Oxygen Isotopes
Question
5 answers
I am doing a research on mass extinction on the Permian-Triassic boundary about 250Ma in Botswana Kalahari Karoo Basin to determine
Causes of extinction
paleo-climate and paleo-environment across the P-T boundary
I am planning on using stable carbon ẟ¹³C and ẟ¹⁸O compositions using ICP-MS method. How does the data obtained from ICP-MS look like?
How do you interpret the data?
Relevant answer
Answer
This might be helpful also. It is a difficult read though!
  • asked a question related to Oxygen Isotopes
Question
6 answers
I’m working on the use of stable isotope ratios in traceability studies of horticultural products. Based on literature and previous studies, I can use any tree part for the analysis when it comes to Sr isotope ratios. However, things change considering H and O, as their isotope ratio may vary considering different classes of organic compounds in plant materials, due to differences in the metabolic pathways of each class (to simplify, let’s consider that all the material was synthetized during the same time frame, e.g. same growing season).
So, I would like to know your opinions about the following points:
1. If I analyze δ2H and δ18O in different tree parts grown in the same period (e.g. shoots, leaves, fruits analyzed as bulk sample), should I expect that the different proportion among classes of organic compounds in each part can lead to a significant difference in their δ2H and δ18O?
2. Analyzing a specific class of organic compounds (after extraction) instead of the bulk sample, should I get the same value in all the different tree parts?
I found several papers discussing this specific topic but related to C and N isotope ratios, can you suggest me any papers related to H and O? Many thanks.
Relevant answer
Answer
*Recent developments in application of stable isotope analysis on agro-product authenticity and traceability
Yan Zhao, Bin Zhang, Gang Chen, Ailiang Chen, Shuming Yang, Zhihua Ye
PMID: 24128481 DOI: 10.1016/j.foodchem.2013.08.062
Abstract
With the globalisation of agro-product markets and convenient transportation of food across countries and continents, the potential for distribution of mis-labelled products increases accordingly, highlighting the need for measures to identify the origin of food. High quality food with identified geographic origin is a concern not only for consumers, but also for agriculture farmers, retailers and administrative authorities. Currently, stable isotope ratio analysis in combination with other chemical methods gradually becomes a promising approach for agro-product authenticity and traceability. In the last five years, a growing number of research papers have been published on tracing agro-products by stable isotope ratio analysis and techniques combining with other instruments. In these reports, the global variety of stable isotope compositions has been investigated, including light elements such as C, N, H, O and S, and heavy isotopes variation such as Sr and B. Several factors also have been considered, including the latitude, altitude, evaporation and climate conditions. In the present paper, an overview is provided on the authenticity and traceability of the agro-products from both animal and plant sources by stable isotope ratio analysis.
*Hydrological cycle research by D & 18 O tracing in small watershed in the loess hilly region
Xu Xuexuan 1,*, Zhao Jiaona 2,*, Zhang Xiaoni 3,*
International Soil and Water Conservation Research, Vol1, No3,2013, pp75 82 Mar 18, 2015
The objective of this study was to determine the mechanisms of the hydrologic cycle in the loess area in China. Sixty eight water samples from precipitation, soil water of the 0 – 4 m layer, surface water in the valley, ground water (spring and well) were collected and the Deuterium (D) and Oxygen – 18 (O) of these water samples were analyzed to interpret the relationship among those waters in the watershed in the loess hilly region during 2005 – 2009. The results show that: the D & 18O of precipitation in Yangou was consistent with that of Xi'an, apparently the north migration of water vapor in Xi'an; according to the correlations among the differential waters in D & 18 O, confirmed that precipitation recharge could account for most of the sources of valley flow, with part of the recharge water going to soil water recharge. The D & 18O of groundwater were very close to that of precipitation, likely the soil preferential flow was dominant in groundwater recharge although the infiltration had a certain lag. Under the influence of rainfall and evaporation, the response of the soil moisture profile, and its D & 18O profile were different. The soil moisture had the strong influenced layer in the 0 60 cm range, a weak impacted layer in 60 160 cm, and a stable layer below 160 cm. It was shown that the soil evaporation depth could be up to 160 cm because the D & 18O changed in that depth. The study could increase our understanding of the magnitude and pattern of the hydrologic cycle, which should improve water resources management in the watershed scale.
Similar articles
*Authenticity and quality of animal origin food investigated by stable-isotope ratio analysis.
Vinci G, Preti R, Tieri A, Vieri S. J Sci Food Agric. 2013 Feb;93(3):439-48. doi: 10.1002/jsfa.5970. Epub 2012 Dec 4. PMID: 23209000 Review.
  • asked a question related to Oxygen Isotopes
Question
5 answers
I hope you are doing well.
Could you please help me calculate the fluid oxygen isotope range also source temperature based on the analyzed magnetite's oxygen isotopic data?
Is there any excel file for automatic calculation?
Relevant answer
Answer
Hi Afshin,
It depends a bit on the temperature range that you are interested in. For 18O/16O fractionation at high temperatures, it is probably best to use the fractionation factors by Zheng et al. (1991, GCA) that are based on the vibrational frequencies of the molecules. For triple oxygen isotope fractionation, one could use the theoretical values by Hayles et al. (2018, GCA). Both papers explain well how to to calculate water-magnetite fractionation at different temperatures. It is important to keep in mind that the calculations give accurate results only at the level of ca. +/- 0.5 per mill in d18O at the very best.
Best wishes,
Stefan
  • asked a question related to Oxygen Isotopes
Question
3 answers
Strong evaporation of soil water in arid areas, so how to compute the evaporation of soil water according to the hydrogen and oxygen isotopes?
Relevant answer
Answer
The isotopic composition of the remaining water depends on the temperature and the isotopic signiture of the air moisture because of possible back diffusion.
My best guess:
Gat, Joel R. (2010): Isotope hydrology. A study of the water cycle. London: Imperial College Press (Series on environmental science and management, 6).
Majoube, M. (1971), Fractionannement en oxygene-18 et deuterium entre
l’eau et sa vapeur, J. Chim. Phys., 197, 1423–1436.
Best regards
  • asked a question related to Oxygen Isotopes
Question
2 answers
how to use ice -core oxygen isotope value to establish precise chronology?
Relevant answer
Answer
Thank you
Sarvat Gull
for your suggestion. Actually I,m looking to calibrate radiocarbon ages (last 40 ka age) using Bchron model.
  • asked a question related to Oxygen Isotopes
Question
4 answers
Hi to all, I did an experiment with drinkable water of a spring (I bought the bottle). I put a part of this water in a fridge (water with natural CO2) in a large plate and I left in the fridge for 3 days (without any cover). My aim was to enrich water with heavy isotopes and to model the change of δ18O and δ2H during the fractionating.
The temperature in the fridge was around 0 and 1 °C. In the end of the experiment 16% of water was lost.
I measured in the laboratory (by IRMS spectrometry) the isotopes and these are the results:
· δ18O before the treatment: -8.7 and after the treatment in the fridge -6
· δ2H before the treatment: -58.5 and after the treatment in the fridge --46.3
I tried to model the changes of δ18O and δ2H during the fractionating and I used these formulas (regarding the transition ICE-VAPOUR):
For δ18O Majzoub (1971) plus O'Neil (1968)
For δ2H Majzoub (1971) plus Arnason (1969)
Using these formula I have a good result for the δ18O because at f=0.84 (that means 100-16% of water lost) I have more or less -6, but for the deuterium normally I must have -36 instead of -46.3.
How can I explain these results? Do you have some ideas?
It can be that the humidity affected the deuterium? and if yes, how the humidity affects the deuterium and which could be the formula?
Relevant answer
Answer
Good to see reference waters were used. However, strictly speaking, the waters used do Not cover the range of the VSMOW/SLAP scale. This is of particular concern for scale normalization of measured d2H values. For d2H the VSMOW/SLAP scale is 428 o/oo wide. Your ref waters only cover 36% of that scale which will result is some skew (see this article for examples how choice of scale anchors can affect results:
That being said, since your water sample have d2H values in between the end points given by your ref waters, impact of skew should be minor to being not significant.
Did the water you put in the fridge really freeze solid completely or did it just cool down to fridge temperature with perhaps a few slivers of ice present? You say you based your caluclations on the system ice/vapour, i.e. on ice sublimating directly into the gas phase. How would the result of your calculation for d2H change if you based them on the system liquid/vapour at 0 C (epsilon 2H = -101.0)? How would things change if you based calculations on a combination of phase changes, i.e. ice/liquid at 0 C (epsilon 2H = +19.3) and liquid/vapour at 0 C (epsilon 2H = -101.0)?
  • asked a question related to Oxygen Isotopes
Question
2 answers
I am only in the beginning phases of this research and could use all the help you are willing to give! If anyone has anything that may be of use to me, be it the oxygen isotope concentrations or articles about Neanderthal breathing habits please send it this way! Thank you!
Relevant answer
Answer
Hi Christian,
The dates provided by Lisiecki and Raymo (2005) are frequently employed/a good starting point:
Reference:
Lisiecki, L.E. and Raymo, M.E. 2005. A Pliocene-Pleistocene stack of 57 globally distributed benthic δ18O records". Paleoceanography. 20: doi:10.1029/2004PA001071.
Dates:
Brief guide:
Full paper:
These authors continue to refine their scheme...
Good luck with your research - if this week's reports on Neanderthals having 'Swimmer's Ear' are accurate, they must have been good at holding their breath!
All the best, Fred.
  • asked a question related to Oxygen Isotopes
Question
3 answers
I am trying to analyze some seawater and sea ice core samples for hydrogen and oxygen isotopic composition using a high temperature conversion — isotope ratio mass spectrometry method. I've seen groups mention that the salt in those samples can make analysis challenging, but I can't find specifics. What should I expect and what extra steps should I take for samples like these?
Any suggestions or methods/papers would be appreciated.
Relevant answer
Answer
Issam Moussa's cautionary tale prompts me to add the following. It is possible to analyse freshwater, ice / snow melt and precipitation by injection using a syringe (barrel volume 1 - 1.5 uL) fitted with a needle of 26 gauge and 70 mm in length. Surprisingly (or perhaps not), it is easier to inject water (injection volume 100 - 120 nL) into an HTC/EA manually rather than by using an autosampler. Injecting manually, the analyst can feel if friction would cause the plunger not to hit home in a smooth continued fashion. Rather than to proceed (and damage the syringe in the process as an autosampler would) one aborts the run and either replaces the plunger or uses a spare syringe. We recently published the results of a survey of 127 freshwater lakes. Water samples were analysed for d2H and d18O values by liquid injection on to a HTC/EA-IRMS system. Samples and reference waters VSMOW, GISP and SLAP were injected in replicates of 5 with results from the 1st injection discarded in case of any memory (carry over). Typical error of measurement for average d2H and d18O values of 4 injections was ±0.64 and ±0.19 ‰ respectively.
  • asked a question related to Oxygen Isotopes
Question
3 answers
how can I know whether or not my result is influenced by the bacteria
when I culture the diatom and harvest the culture solution before my detecting of the figure about the phosphate oxygen isotope?
Relevant answer
Answer
Hi Lin
Your question isn't very clear. Do you want to make your xenic algal sample bacteria free or you already have a stock axenic algae, but facing problem of bacterial contamination during the course of experiment?
If it is the first, then as Abhishek Mukherjee have said there are many methods to do so. you can easily search for well documented literature regarding it. Try to use a combination of physical methods and antibiotic treatment. Physical methods will include gentle vortex, low frequency sonication to ward off attached cells followed by low pressurized filtration of the sample through 3-5 um filter paper (depending upon your algae size) and re suspending the cell pellet in sterile liquid media. Additionally, you can do 3000-400 xg centrifugation these will leave maximum bacterial cells in the supernatant part. It is difficult to completely eradicate bacteria from the sample using physical method. But, is very effective in removing much of the bacteria.
Further, you can use plating method (if your algae can grow very well on agar plates) or antibiotic test to completely remove the bacteria. Regarding antibiotic treatment, some antibiotics (such as chloramphenicol) have negative effect on algae growth. So, be careful when using antibiotics as it might affect your further experiment results.
To know which antibiotics to use, you can do a antibiotic susceptibility test using antibiotic susceptibility kit (contains many small paper disks impregnated with different antibiotics).
If your question is regarding maintaining an axenic culture without being contaminated. You need to work in a clean place (preferably a sterile Laminar hood) and with sterile utensils. Always open your culture bottle inside the sterile hood and near the Bunsen burner. And most importantly, always follow microbiological aseptic techniques.
Good luck,
  • asked a question related to Oxygen Isotopes
Question
2 answers
Solubility of apatite is highly addressed in mineralogical and material studies.
Heating is one of the major processes in apatite industry. In this study, synthesized
hydroxylapatite (HAp), geological fluorapatite (FAp), and bone bioapatite (BAp) were heated
at various temperature (100-900 oC) for analyses. The mineralogy and solubility of the three
apatites were analyzed by XRD, ATR-IR, and ICP. Release of Ca and P in water for BAp
reach the maximum when heated at 200 oC, i.e., 0.215 mmol/L for Ca and 0.106 mmol/L for
P. The value is higher than the maximum values (heated at 900 oC) of solubility for HAp and
FAp. The heating temperature at 600 oC is a re-crystallization point for all the three types of
apatites. Especially, the crystallinity of BAp is significantly elevated at >600 oC. Phase of
geological FAp is relatively stable during heating up to 900 oC. Phase of =-TCP is present
when heating HAp at 800 to 900 oC. In addition, BAp is transformed to the resemblance of
HAp. However, no =-TCP was detected for BAp during heating between 800 to 900 oC,
which is probably due to its Ca-deficiency.
materials and fertilizer.
Relevant answer
Answer
thank you very much
  • asked a question related to Oxygen Isotopes
Question
3 answers
One of my students got extremely negative values in oxygen isotopes for diagenetic carbonate structures << -20 per mil V-PDB. The issue is I have never seen any paper with values that negative before. I'd like to understand the implications for such odd values. I'd appreciate if anyone can point me toward relevant papers.
Relevant answer
Answer
How far away are the igneous rocks? How big is the igneous body? What kind of carbonate did you investigate? It is known that e.g. intrusions emit lots of water during cooling. Thus, if your sediment has (or had during the cooling of the intrusion) a high permeability the water might significantly alter the isotope values.
  • asked a question related to Oxygen Isotopes
Question
5 answers
Which lab shall I use? Any recommendations?
Relevant answer
Answer
  • asked a question related to Oxygen Isotopes
Question
7 answers
I have generated d18O data of foraminifera from marine core. I need to correlate it to LR-04 benthic isotope stack.Is there any software other than analyseries which may be used for doing this.
Relevant answer
Answer
Thanks very much Ferdinand Oberle for this paper and link.
  • asked a question related to Oxygen Isotopes
Question
4 answers
Problem is slove
Relevant answer
Answer
What was the original carbonate mineralogy, LMC or HMC/Aragonite (during the Jurassic it could've been either)?
What is the current mineralogy? If it's different, then your rocks have undergone neomorphism (near certainty that they did) and your d18O values reflect the temperature and water d18O during neomorphism.
Then ask yourself the following questions:
1.) What was the temperature of neomorphism/formation?
2.) What were the potential fluid sources?
3.) Was there a meteoric fluid source?
4.) What were possible d18O values of your fluids?
Then with that data, plug it into calcite-water fractionation equation e.g. Friedman and O'Neil (1977) and see if you get realistic values.
Examples:
Seawater with a d18O of 0 per mil VSMOW at 25 oC produces a calcite with -2.45 per mil VPDB.
Seawater with a d18O of -2 per mil VSMOW at 25 oC produces a calcite with -4.39 per mil VPDB. (The upper end of your values)
Seawater with a d18O of -2 per mil VSMOW at 45 oC produces a calcite with -8.08 per mil VPDB. (The lower end of your values)
Now it's up to you to figure out if those are realistic temperatures or fluid d18O based on other data. I agree with Xue-Ming Yang that even if meteoric waters interacted with your rocks, the d13C may still reflect the original carbonate values.
To see an example of how to do this you can check out my publication:
And the calcite-water fractionation equation is below:
Good luck!
  • asked a question related to Oxygen Isotopes
Question
3 answers
To obtain the isotope composition of carbon and oxygen of an solution of CaCO3 in water the carbonate is precipitated as SrCO3.Then SrCO3 is analyzed by mass spectoscopy. Can this material be handled routinely in the same way as CaCO3 or does it need an extra protocol. In other words, can SrCO3 be analyzed in an array together with CaCO3 samples?
Relevant answer
Answer
In principle, it will be possible to analyze SrCO3 for 13C and 18O abundance by acid digest with anhydrous H3PO4. As with analysis of CaCO3 by acid digest one should, nay must analyze at least two carbonate reference materials contemporaneously alongside one's samples (i.e. as part of the same batch run = Identical Treatment principle). Using accepted and measured d13C (d18O) values of the carbonate RMs as end-points, the resulting linear correction equation will isotopically calibrate sample d13C (d18O) values and therefore compensate for any fractionation at the same time.
That being said, there is actually no need to precipitate dissolved [CO3]2- as either SrCO3 or BaCO3. Granted, either carbonate is less soluble in water than CaCO3 but the differences are not massive. Solubility product of BaCO3 is 2.58x10-9 mole2/L2 which is marginally less than that of CaCO3 with 3.36x10-9 mole2/L2. In other words, one can precipitate dissolved [CO3]2- as easily as CaCO3 by increasing the [Ca]2+ concentration of a sample solution so it is well in excess of 5.8x10-5 mole/L. As long as this is the case, CaCO3 will precipitate.
  • asked a question related to Oxygen Isotopes
Question
3 answers
sediment chronology related question
Relevant answer
Answer
I do not quite understand your question but this is dating sediment chronology related question I do not think stable isotopes 13C and 15N will help you to date chronology your sediment samples.
  • asked a question related to Oxygen Isotopes
Question
3 answers
We are looking for a partner or a provider for stable isotopic analysis (S, C and O or any of these) on pore water and water column. 
Relevant answer
Answer
PLEASE  ASK DR E. KEREPERTZIS DEPARTMENT OF GEOLOGY
  • asked a question related to Oxygen Isotopes
Question
10 answers
Relevant answer
Answer
I agree, I suspect that your carbonate is being produced chemically, not biogenically.
The source of carbonate ions in that reaction will be from carbon dioxide produced by the respiration of microorganism ..
  • asked a question related to Oxygen Isotopes
Question
9 answers
Hello everybody,
I'm interested to understand about the effects of isotopes on properties of a molecule. For example in hydrogen, helium or oxygen (which have isotopes) what is the general expectation on some properties like critical temperature, critical pressure, critical volume and normal boiling point and ideal liquid density of isotopes?
I mean as an example is it true to say that we should expect higher value in volume and density in heavier isotopes? or higher normal boiling point in heavier isotopes like D2 rather than H2?
As an example the normal boiling point of 16O16O is -182.95 C, is it true to consider the normal boiling point of 16O18O (which is heavier) a value like -182.5 C?
So if I conclude my question, what is the value of heavier isotopes against lighter isotopes in following properties: (answer by bigger or lower):
Normal boiling point?
Ideal liquid density?
Critical temperature?
Critical Pressure?
Critical volume?
and Acentric factor?
Thanks in advance.
Meysam.
Relevant answer
Answer
Physical propetrties of D2O vs. H2O
after Brodskij, Chemistry of Isotopes, Moscow 1952:
Density at 25oC 1.10469 vs. 0.99704
Normal boiling point 101.42oC vs. 100.00
Critical temperature 371.5oC vs. 374.2oC
Critical Pressure   218.6 at vs. 218.5 at
  • asked a question related to Oxygen Isotopes
Question
4 answers
In addition, does anybody has vapor pressures and other properties of oxygen isotopes like 16O18O?
I really need some experimental data or references which I could be able to have these properties.
Thanks in advance.
Relevant answer
Answer
Dear Meysam,
I am not an expert, so I am not able to give you more help. However, I will point out, in case you are not already aware of it, there is a useful search engine called Google Scholar to be found at https://scholar.google.com . The trick with it is to find the correct search string. 16O18O properties gives 4000 hits, rather too many. 16O18O boiling point gives less but you may be more successful with 1618O condensation temperature.
I found this http://epswww.unm.edu/media/pdf/contents.pdf using the search string 16O18O properties condensation It may be useful.
PS Thanks for voting up my previous answer.
  • asked a question related to Oxygen Isotopes
Question
1 answer
i want to know about the formation of NH4(gas or aq)  from the combination N2 gas with H2gas; below the conditions.
just i think that N2 gas derived from magma reservoir,
but the production mechanism of H2 gas maybe CH4 and H2S gas from magma gas ? or by Desulfovibrio ? or abnormal meteoric water? or fracture of silicate minerals by earthquake (because very active volcano be located around)
the conditions
in  calc-alkalic andesitic and rhyolitic magma system, volcanic and organic rich sediments covered submarne vent system in garben caldera like crater. under the 20bar, 473K. seawater pH about 7~8, hydrothermal fluids near the vent system showed pH 5~6 (from diffusing hydrothermal fluid).
from the chemistry of pore water fluid in sediment core showed high concentration of ammonia.   
from the oxygen isotope data that it is possible to mix among seawater, meteoric water and magma water.
Relevant answer
Answer
Ammonia is formed from N2 and H2 in the Haber process. That requires:
(i) medium temperature (≈500oC)
(ii) very high pressure (≈250 atmospheres, ≈25,500kPa)
(iii) a catalyst (a porous iron catalyst prepared by reducing magnetite, Fe3O4).
Osmium is a much better catalyst for the reaction but is very expensive
It would be an interesting project to investigate whether those condition occur within  a volcano. There is more about the Haber process here: http://www.chemguide.co.uk/physical/equilibria/haber.html
  • asked a question related to Oxygen Isotopes
Question
3 answers
The emphasis is on triple oxygen isotope system where mass-dependent fractionation is operating. A mass loss due to evaporation of water may cause an enrichment of heavier isotope (d18O compared to d17O). To model this scenario, I may need a reference to start with. I would apprecaite receiving suggestions regarding dehydration of phyllosilicates (having -OH group) during thermal metamorphism at ~850C. Assuming it is an open system allowing loss of part of evaporated water (enriched in d17O compared to d18O) while the rest of it is being recondensed. This scenario represents thermal metamorphism occurred on a H or L ordinary chondrite (types 5 or 6) parent body/ies (stony asteriods) assuming type 3 OC as a precusrsor having phyllosilicates formed after aqueous alteration.
  • asked a question related to Oxygen Isotopes
Question
2 answers
Generally, there are three partial reactions during gibbsite dehydroxylation. Gibbsite will transform into boehmite at about 200℃. If I know the H/O isotope value of gibbsite, how can I get the value of boehmite. Alternatively, anyone knows the fractionation faactors between them.
Relevant answer
Answer
This link may help..
Surface Complexation Modeling: Gibbsite ( Book) by Karamalidis, A.K., Dzombak, D.A.
Incremental vacuum dehydration-decarbonation experiments on a natural gibbsite (α-Al(OH3)): CO2 abundance and δ13C values. by Tabor, N.J., Yapp, C.J. 
(2005) : Geochimica et Cosmochimica Acta
  • asked a question related to Oxygen Isotopes
Question
10 answers
I have a  Speleothem isotope record of Indian summer monsoon(NW Himalan region) in which oxygen isotope shows wetter phase (16O enriched values). At the same time for the same speleothem (same depth and time as for oxygen) carbon isotope record shows C4 vegetation(13C enriched values).
 How can it be possible? In which condition would it happened?
Because in tropical region the vegetation is governed by rainfall. If more rainfall then It should be C3 type vegetation(12C enriched) vegetation.
Relevant answer
Answer
please go through the article "Sinha et al., A leading mode of Indian summer monsoon precipitation varibility during the last millennium" GRL, 38, (2011)
  • asked a question related to Oxygen Isotopes
Question
3 answers
Dear Researcher,
I am critical about a porphyry Cu-S ore occurrence while working on a porphyry granitoid in a cratonic shield of NE India . As my study shows positive indications in many parameters I studied like Sr and S isotopes, hypogene alteration pattern, detail geochemical signature etc. I need to investigate oxygen isotope and fluid inclusion to enhance my claim for drilling as geophysical works seems to be difficult in view of inaccessibility.
Relevant answer
Answer
Can you give more information by email please.
Martin feely
  • asked a question related to Oxygen Isotopes
Question
6 answers
monsoon pollen records, oxygen isotope ratio etc. 
Relevant answer
Answer
You may contact to Dr. Borgaonkar at IITM Pune or Prof. Ramesh from PRL ahmedabad.
  • asked a question related to Oxygen Isotopes
Question
10 answers
Hello everyone,
I asked a previous question as to whether dense ash aggregates (or "acc-laps") have ever been made in any wind tunnel lab thus far in their fully formed sub-spherical or ellipsoïdal shape ?
The answer has been: "not yet", even though this would allow to more closely simulate mixed phase aggregation under more realistic in situ ashcloud conditions.
I am wondering if any accretionary lapilli greater than about 10mm across or so have ever been collected immediately upon reaching the ground and studied immediately, or preserved in a cold box (to prevent them from any melting) and studied in the lab (eg. on a cryogenic SEM stage, or to measure their in situ temperature, and recover inner fluids from the intergranular space....) ?
The reason is that there is the hypothesis that they form like hailstones by riming, once they grow above a size characteristic of the drop break-up limit (5-6mm across). If this "volcanogenic hailstone" hypothesis is correct, then my expectation is that a proportion of accretionary lapilli larger than about 6mm diameter should still be frozen upon reaching the ground (especially if above-ground températures are close to 0°C; if not partial melting takes place), so that somewhat larger ones (say 10mm diameter ones) may still be frozen (despite partial melting) and still contain inner ice upon landing on the ground.
Has anyone checked for this ?
Assuming for a moment that larger sub-concentric acclaps can be sampled immediately, preserved and analysed for oxygen isotopes of any trapped ice water, then this could provide valuable data as to the temperature environments through which the acc-laps have been recycled again and again in the volcanic cloud before ultimately falling out.
Analogous oxygen isotope ratio studies  of the subconcentric layers of hailstones from severe thunderstorms have provided such information in that case.
I am looking forward to hearing back.
Best wishes and kind regards,
Gerald
Relevant answer
Answer
Hello Gerald, Ulli, Volker,
There quite a few nice examples I'm aware of where accretionary lapilli were sampled soon after fallout. One is the 2002 study by Bonadonna et al. on the 1995-1999 eruption at Montserrat (Geol. Soc. London Memoirs). Another is the 2009 eruption of Redoubt, Alaska, described by Kristi Wallace et al. in JVGR, 2013. The latter samples provided the basis of my study of 'volcanic hail' using radar observations and plume modeling with ATHAM in Nature Communications. As suggested by Gerald, these samples were indeed frozen upon landing, though that's not too surprising for an Alaskan eruption. It is clear from lab experiments that neither ice nor salt precipitates are required to grow aggregates >1cm diameter. I do not think aggregates need to undergo freezing, however, it does seem to be very common and does affect their growth rates and internal structure. 
There are also some gorgeous, layered accretionary lapilli from the 18 May 1980 eruption of Mount St. Helens, which have been archived for the past 35 years. I've recently thin-sectioned these samples and am currently working on comparing their internal structures to the eruptive stratigraphy and photographic record of the eruption dynamics. Hopefully I'll be presenting this work at the Cities on Volcanoes meeting in Chile this year. Ulli and I were talking about organizing a workshop on ash aggregation there if there's enough interest. 
All the best
Alexa
  • asked a question related to Oxygen Isotopes
Question
3 answers
It is well known that stable oxygen isotopic composition (δ18O) has been widely used to trace natural hydrological processes.  In modern ocean research, δ18O has been used to obtain information on the origin and mixing of water masses, such as freshwater mixing, evaporation, precipitation and sea-ice formation. The  δ18O of seawater is influenced by these foregoing factors. However, will  δ18O of seawater be influenced by biochemical processes? Such as Photosynthesis and respiration? whether δ18O of seawater can be influenced by  biological fractionation of δ18O (Dissolved Oxygen) in seawater? Can anyone provide me some references about this? Thanks!
Relevant answer
Answer
That is what I meant by mixing, i.e., mixing of different source-type waters.
  • asked a question related to Oxygen Isotopes
Question
4 answers
What does the carbon and oxygen isotopic compositions of pedogenic carbonates tell us about the climate during which they formed, when they show positive, negative relationship, or even noncorrelation?
Relevant answer
Answer
13C/12C ratios of  pedogenic carbonates are generally related to the carbon isotopes of atmospheric CO2, soil-respired CO2 and soil carbonates. There is a complicated relation among them. There would be no direct relationships between C and O isotopes. If it shows some, diagenesis must be imprinted after deposition.
  • asked a question related to Oxygen Isotopes
Question
5 answers
Ferromanganese crust is authigenic precipitation on surface of rocks in the deep ocean. As it is formed very slowly, its oxygen isotope should be equilibrium with that of the ambient sea water. However, different proportions of precipitated minerals, such as δMnO2, FeO(OH), among different layers make it complicated to identify the fractionation factors. If resolved, the oxygen isotope profile would be useful neither in establishing the age model of ferromanganese crust or in the past changes in the ocean envioronment. So, so anyone provide me any clues to resolve this problem, for example, the oxygen isotope fractionation factors between sea water and the oxides?
Relevant answer
Answer
Dear Fan:
There was a USGS Open File Report published in 1985 that measured the O and H isotopes of ferromanganese crusts and nodules to use as a comparison for similar data produced for Mn deposits in the geological record, which is the focus of the report.  O isotopes should be useful as a paleoceanographic indicator and especially as a new tool for geochronology of crusts.  One approach would be to create 2-X-ray line delta MnO2 in the lab and feroxyhyte or ferrihydrite and determine the fractionation factors using those--I think that this may have already been done.  Another approach is to analyze samples with different ratios of delta MnO2 and feroxyhyte, based on geochemistry.  The 1985 report is attached here--see Table 2.  
  • asked a question related to Oxygen Isotopes
Question
3 answers
I am analyzing the relationship between stable isotope (d13C & d18O) from tree-rings and climate variables. And I want to interpret the response of d13C and d18O with monthly precipitation, humidity, temperature, etc. I found significant differences between tree species and sites (Humid and Dry forest) which I can only attribute as a noise related to specific-species and unknown factors. And inside of these unknown factors I was thinking if the lenticels could have a significant influence in the isotope fixation process, mainly the d13C. Two of my tree species have lenticels in the trunk (Maclura tinctoria) and in the young branches (Cedrela montana), and both are defoliated of 4 to 6 months in the year.
Since the lenticels are pathways for gas exchange similar to stomata, would it be possible that lenticels can play an important role in the carbon and oxygen fixation on the wood, and if so, how?
I will appreciate very much your comments.
Kind regards
Relevant answer
Answer
13C composition of plant tissue is primarily a function of CO2 fixation (C3 v. C4 pathway).  However, if a plant is water stressed d13C values in plant tissue and endproducts such as sugars or lipids become more positive since closure of stomata results in CO2 fixation now drawing from a limited CO2 reservoir (isotopic fractionation) in contrast to using CO2 from an unlimited reservoir (= atmosphere) when the stomata are open.Plant tissue d13C should not be confused with Farquhar's Delta(d13C) term as proxy for water stress as this term becomes smaller with increasing water stress (or decreasing WUE).
Other, secondary factors influencing 13C composition are temperature and availability of nutrients (minerals) since these impact on biochemical activity.  Deconvoluting these factors from precipitation (as in precipitation level or water stress) will not be easy unless you have (monthly) data for all these to build an input (CO2) - output (tissue C) model that translates these factors into fluxes and turn-over rates.
18O composition of plant tissue is a more complex issue since here we are looking at three precursor pools and not just one as for 13C.  These precursor pools are water, CO2 and atmospheric O2.  The latter is of particular importance when looking at d18O values of lignin or basically any compound in the shikimate pathway.
In analogy to Farquhar's Delta(d13C) term (using d13C of atmospheric CO2 as reference point) a Delta(d18O) term has been defined (using d18O of source water as reference point).  This term becomes more positive as WUE increases.
Due to the 2 amu difference between 16O and 18O isotopic fractionation during biochemical reactions has a much more pronounced impact on plant tissue (plant product) d18O values (cf. H-J Schmidt's papers).  Biochemical reactions (= enzyme activity) are temperature dependent which will make it challenging to correlate plant tissue d18O simply to (monthly) precipitation.
In short, there are plent of processes or factors impacting on d13C and d18O that will make it difficult to determine a (significant) correlation to monthly precipiation levels.  For the reasons mentioned by Guido Bongi already It is quite unlikely lenticles will have a significant effect on d13C and d18O values.
The main drivers for mass discrimination and hence isotopic fractionation are physico-chemical processes such as evaporation/condensation (thermodynamic isotope effect) or chemical processes involving breaking / formation of chemical bonds (kinetic isotope effect).
  • asked a question related to Oxygen Isotopes
Question
10 answers
My carbonate carbon isotope vaues from a Cenomanian-Turonian section (deposited during OAE 2) are depleted by more than 1.5–3‰ relative to contemporaneous marine calcite. Likewise, the δ18Ocarb values  are also low compared to those found in Cretaceous pelagic sediments (Clarke and Jenkyns, 1999). ¿Could a demise of carbonate production explain carbonate carbon and oxygen isotope values depleted relative to contemporaneous marine calcite?
Relevant answer
Answer
Hi Fernando,
Having a r2 = 017 doesn't mean that your carbonate haven't been altered by diagenesis. Especially for d18O values with are very sensible to diagenetic processes, contrary to d13C values, which are more robust.
The paper that Niels have indicated you are a good start for solving your problem I reckon. 
  • asked a question related to Oxygen Isotopes
Question
2 answers
I'm not a scientist in this field, but I was just wondering whether these two datasets could help each other for the benefit of a better understanding of human mobility in the past.
Relevant answer
Answer
This simple answer is No and Maybe.  18O signatures obtained from human bio-apatite (bone and/or teeth) are correlated with 18O signatures of dietary water intake (directly as well as indirectly from fruit and vegetables). The precursor pool of 18O signatures in food and drink is precipitation and the 18O signature of precipitation varies with/depends on distance to open sea, latitude, altitude and temperature, which is why bio-apatite 18O signatures can be used to draw conclusions about human mobility in the first place.
However, even first landfall precipitation 18O composition differs from marine surface water 18O due to isotopic fractionation during cloud formation out at sea and isotopic fraction during precipitation.
Ice core 18O may provide helpful information but that would be limited to ice cores taken in alpine environments (glaciers), i.e. ice core records of terrestrial precipitation.
Marine 18O records as in climate / temperature change records may be useful if it can be shown that particular mass migration events correlate with significant (global) climate change events.
  • asked a question related to Oxygen Isotopes
Question
2 answers
As we know, both cellulose oxygen isotope and leaf wax hydrogen isotope could record the isotope information of precipitation. However, for cellulose, most case studies focus on peat study. For lake sediment, there seldom papers concerned. Could you share your ideas about this? Thanks.
Relevant answer
Answer
During synthesis of cellulose, sucrose cound exchange oxygen atoms with water, so oxygen isotope in cellulose can not reflect oxygen isotope in leaf water completely, but for D in wax, no exchagne between substrate and water during wax synthesis.
  • asked a question related to Oxygen Isotopes
Question
1 answer
i have Oxygen and deutrium concentrations for about 35 springs. i wonder if i can find any method to estimate the reservoir's temperature by using these concentrations
Relevant answer
Answer
You can't. There is no direct relation between the 'reservoir temperature' and the isotopic composition of the water. Most hydrothermal waters are recharched by atmospheric precpitation and the isotope ratios of this precipitation will largely determine the isotope ratios of the water regardless of the reservoir temperatures.
  • asked a question related to Oxygen Isotopes
Question
6 answers
Does anyone have any information on the presence of 16O/18O oxygen isotope ratio in exhaled breath and the presence or stage of cancer?
Relevant answer
Answer
Measured d18O (v. VPDB) values of CO2 exhaled in breath of Central Europeans at rest may range from -3 to +3 ‰.  This will change the moment a person gives a breath samples during and shortly after even moderate exercise (walking; clmibing stairs). In other words, d18O of exhaled CO2 is (not surprisingly) correlated, if not directly influenced by a person's metabolic rate.  For this reason, in all our studies working on diagnistic stable isotope breath tests our protocol stipulated for subjects to be at a rested metabolic state (remain seated comfortably) throughout the test. Prior to adminstering a tracer meal background breath samples were taken -30 min and -15 min.
Since CO2 is equilibrated with body water via the bicarbonate pool, d18O of exhaled CO2 will also depend on the 18O signature of water consumed as part of a person's diet (direct and "indirect" water).  I would therefore expect baseline d18O values for breath CO2 to be different for people living in e.g. Utah as compared to people living in e.g. Florida.
I would find it hard to predict to what degree differences in metabolic rate between cancerous cells and healthy cells will affect d18O value of exhaled CO2 at rest. It's an interesting question though. The only way to find would be to carry out a study with a statistically meaningful number of age, sex and geographic residence matched volunteers and cancer patients.
  • asked a question related to Oxygen Isotopes
Question
2 answers
Hey!
I am analyzing triple oxygen isotopes of carbonates. While scanning on Mass Spectrophotometer (magnetic Field vs Intensity), the Nitrogen peak (mass 28, Cup 3) is very high. I didn't find any leak, is it user error or any suggestions to improve?
Relevant answer
Answer
Since you mention B v. I scanning and signals on Cup 3 it sounds to me you are actually using an isotope ratio mass spectrometer (IRMS). In these multi-collector instruments the three cups are used for collecting masses 28, 29 and 30 (or 44, 45 and 46) since the isotope abundance measurements of 15N (or 18O or 13C) are based on determining abundance ratios, e.g. 29/28 and 30/28 or 45/44 and 46/44. Given the difference in abundance between m, m+1 and m+2 the three cups are fitted with different resistors resulting in different amplification of measured ion currents so all signals are of a similar level.  Typical relative amplification factors for cup 1, 2 and 3 are 1, 100 and 300 (333 actually), respectively. For this reason, during a background scan (changing B) m/z 28 (either 14N2 or 12C16O) will yield a huge signal on cup3 given that 14N, 12C and 16O are the most abundant stable isotopes of nitrogen, carbon and oxygen. Under normal operating  conditions m/z 28 will fall into cup 1 (while m/z 29 and 30 will fall into cups 2 and 3, respectively).
  • asked a question related to Oxygen Isotopes
Question
9 answers
I'm mainly interested in low temperature carbonate formation and with no biological influence.  
Relevant answer
Answer
Speleothems are a poor example for seeking an absence of oxygen and carbon isotopes co-variation. This is because in most cases speleothem deposition occurs out of equilibrium and co-variation is common due to kinetic effects. For example, cave seasonal ventilation is the primary factor controlling the pCO2 contrast between the dripwater and cave atmosphere. When drip pCO2 is higher than air cave pCO2 the CO2 outgassing causes significant isotope fractionation leading to co-variation between the oxygen and carbon isotopes in the residual bicarbonate in the drips and subsequently in the stalagmites.
  • asked a question related to Oxygen Isotopes
Question
2 answers
silt size samples gotten from drilled holes is to be analysed for carbon and oxygen isotopes. which analytical technique would give the best result? and what is the procedure for preparation of the samples for such analysis?
Relevant answer
Answer
The best method is published by McCerea 1950, which is for CO2 extraction from CaCO3. If you will to analyze siderites you have to modify it a bit, see attachment.
  • asked a question related to Oxygen Isotopes
Question
7 answers
I would like to measure the oxygen isotopes of soil. Is there any precize measurement methods and protocol? Please share.
Relevant answer
Answer
Yes, Isotope ratio mass spectrometer (IRMS) can be used for the analyses of oxygen isotope in soil as well as in water
  • asked a question related to Oxygen Isotopes
Question
4 answers
I am currently studying dolomitic limestones from the Upper Triassic and my samples of dolomite and calcite, after being measured for C and O isotopes, it came with the note that dolomite was corrected as being calcite effect at -0.8‰. 
I know that one of the problems is related with the measurement procedure, once it it used phosphoric acid, but it may be also related with the dolomite problem, what kind of reaction formed the dolomite....
Thank you in advance.
Relevant answer
Answer
You will find all your answers in this recent paper:
Kim, S.-T., T. B. coplen, and J. Horita (2015), Normalization of Stable Isotope Data for Carbonate Minerals: Implementation of IUPAC Guidelines, Geochimica et Cosmochimica Acta.
  • asked a question related to Oxygen Isotopes
Question
10 answers
I would like to get carbon and oxygen isotope composition of carbonate from organic-rich calcareous tufa (bulk). What is a suitable way to remove organic matter from the sediment? Is roasting of the sample at 380°C a reasonable way?
Relevant answer
Answer
I agree with Sonja. To analyze carbonate C- & O-isotopes, you don't need to remove the organic matter. This is standard procedure. Phosphoric acid does not dissolve organic matter. The only problem with elevated organic matter content (especially if it is tar), is that it will probably spoile the vials into wich you put the powder to such extend that you will not be able to reuse them.
  • asked a question related to Oxygen Isotopes
Question
3 answers
Olivine- fresh, directly from mantle or asthenosphere.
Relevant answer
Answer
Oxygen isotope ratios of MORB may be modified if MORB melt interacts with altered oceanic crust. This is most obviously shown in Iceland where mantle derived melt can be substantially modified by crust that has distinctive δ18O because the altering fluid is meteoric water. This effect was apparent even in pre-laser fluorination datasets but has been confirmed for olivines (and other minerals). The results will be more subtle when seawater causes the alteration because its δ18O value is closer to fresh MORB. However, the effect has been seen in backarc basalts form the Lau Basin (Macpherson & Mattey 1998, Chem Geol). The same effect would occur if MORB magma interacted with crust. Both Martin and Arshad are right that the restricted range of oxygen isotope ratios in the mantle combined with the current level of precision make it difficult to recognise source variations in δ18O.
Ocean isalnd- and subduction-related basalts show much stronger case for source δ18O heterogeneity.
  • asked a question related to Oxygen Isotopes
Question
12 answers
Large-scale low-δ18O magmas have been interpreted to have formed by remelting or assimilation of high-temperature hydrothermally altered rocks, such as those found in Iceland basalts and Yellowstone rhyolites. Formation of low-δ18O magma, in most cases, seems to related to rift or extensional tectonic environment. I just wonder whether low-δ18O may be formed at subduction zone and how it happens. Discussion or any relevant reference is appreciated.
Relevant answer
Answer
Subduction settings do not inherently produce low-d18O magmas similar to those found at Yellowstone and Iceland, although there are examples of volcanoes that are formed through subduction and produce low-d18O magmas. Bindeman and others have found some of these in Kamchatka, although the magma d18O values are not as low as are seen at Yellowstone. The low-d18O magmas of Kamchatka are typically associated with larger caldera-forming eruptions that produce ignimbrites, which are associated with similar processes (e.g. rifting or caldera formation) that are found at Yellowstone and Iceland. Therefore, it is not the process of subduction that produces the low-d18O magmas, but instead the later incorporation of low-d18O country rock or previously erupted and hydrothermally altered rock that produce the low-d18O magmas. I attached an article by Bindeman et al. (2010) that includes a lot of d18O data on Kamchatkan volcanoes if you are interested.
  • asked a question related to Oxygen Isotopes
Question
13 answers
Where I can find such a laboratory for oxygen isotope analysis in Europe?
Relevant answer
Answer
Hi
I recommend you to contact Heather Stoll at University of Oviedo (Spain). As far as I know, she is one of the pioneers in geochemistry with coccoliths and diatoms and her lab is a good choice.
Al the best
  • asked a question related to Oxygen Isotopes
Question
5 answers
I want to use Cramer et al. (2009) raw data of oxygen and carbon isotopes for a very specific time period (around 2 Ma long) to compare it to my oxygen and carbon isotopes from terrestrial record. My aim is to show that my site is affectd by global factors by comparing Cramer's data with mine. I don't have the same sample resolution as Cramer's: he has about 1000 data points while I have about 300. How can I solve the problem of difference in data resolution? Which methods would you suggest to address this issue?
I also would like to statistically compare my data with Cramer's, but my data is terrestrial so the oxygen isotope values are much lower (around -7 per mil). I would like to be able to compare the trends, not the actual values. Would anyone know which test(s) I could use?
Relevant answer
Answer
Very nice Julie,
I would suggest to you R as very flexible and powerful tool and you can always count on its large community of users to help you out. There are a number of e-mail groups dedicated to specific research areas with R. Good luck with your research.
  • asked a question related to Oxygen Isotopes
Question
4 answers
I am undertaking some chemostratigraphic work with carbon and oxygen isotopes in carbonates. I have used basic petrographic techniques and (cold) cathodoluminescence to gauge diagenesis and alteration in my samples, though I am interested to hear about experiences other researchers may have had and what techniques they have used. Cheers!
Relevant answer
Answer
Dear Mrs. Betts,
if you want to get a full-blown picture of your rock samples as to the degree of alteration you have to used the various mineralogical methods from XRD, SEM-EDX and thin section through image-providing techniques for quantification. They are classical but there is no other choice. If you suspect of argillitisation, CEC and quantitative measurements in XRD are recommended as it is the application of IR -spectroscopy. Should you have further questions, iI can provide you with papers addressing these problems. I am especially focused on clay mineralogy, which might be one of your stumbling blocks as you mention gauge in your opening address.
Best regards
Harald G. Dill
  • asked a question related to Oxygen Isotopes
Question
6 answers
I assume that apatite mineral in the lunar material is reacting with HCl at 75 degrees when I leach samples to remove any terrestrial contamination. The reason for this assumption is that the oxygen isotope compositions of unleached and leached bulk materials are different, i.e., leached are heavier than the unleached and it could happen if apatite reacts with HCl during leaching process causing -PO4 to go out into the water and ultimately out of the material to be analyzed for oxygen isotopes. Yet another assumption that it could happen only if apatite has heavy oxygen isotopes than the bulk material. I'd appreciate your feedback and suggestion if I could use any other chemical to remove terrestrial contamination (mostly carbonates and oxides) without disturbing the apatite in lunar samples. Thanks!
Relevant answer
Answer
Quite simply yes.
Leaching apatite is a standard way to separate the REE fraction of the phospahet from the silicate.
  • asked a question related to Oxygen Isotopes
Question
2 answers
Stretching with respect to calibration
Relevant answer
Answer
Depends on what you mean by "stretching" for calibration?  If your question relates to 18O abundance measurements by IRMS then the answer is yes; scale normalization of measured d18O value to the VSMOW scale is a muist.  The calibration equation is: scale calibrated d18O = stretch x d18O measured + off-set; stretch factor and off-set are determined from the comparison of measured with accepted d18O values for 2 reference materials of different d18O values.  The requirement for scale calibraton is due to a phenomenon called "scale compression" and the resulting need of scale calibration to achieve comparability of isotope abundance data between different laboratories.  Ideally this is achieved by contemporaneous analysis of matrix matched reference materials when analysing samples.  For example, when analysing organic compounds for 18O one would also analyse reference materials IAEA601 and IAEA602 to normalize measured d18O values on the VSMOW scale.  For 18O analysis of (bio)phosphate you could use the 18O standards reported by Halas et al. (36. S. Halas, G. Skrzypek, W. MEIER-AUGENSTEIN, A. Pelc, and H.F. Kemp (2011): “Inter-laboratory calibration of new silver orthophosphate comparison materials for stable oxygen isotope analysis of phosphates”; Rapid Commun Mass Spectrom., 25, 579-584; DOI: 10.1002/rcm.4892).
  • asked a question related to Oxygen Isotopes
Question
4 answers
As I know, palaeoclimatologists use benthic foraminifera oxygen isotope to reconstruct the ice volume. However, this contains both Arctic and Antarctica information. Shall we separate the signal? Thanks.
Relevant answer
Answer
I agree with K.G. Miller that from 5 ka onwards ice sheets in both polar regions are stable.
  • asked a question related to Oxygen Isotopes
Question
10 answers
In this paper, Lonnie mentioned the precipitation regime of Guliya is monsoonal, however, the oxygen isotope of Guliya is obviously different from classic monsoon-dominated areas in East Asian? Could you share your idea,thanks.
Relevant answer
Answer
The Himalaya Mountains are a barrier for the Indian Monsoon winds. It is likely that it is splitted into two branches. One enters the Tibetan Plateau via the Brahmaputra Valley and the other one from the southwestern part of the Tibetan Plateau. It is still under discussion if the Indian Monsoon also enters the Plateau directly crossing the Himalaya Mountain range. However, if you have these two branches, then you will have different isotopic signatures due to the different transport pathways.
I hope this will help you.
Cheers
  • asked a question related to Oxygen Isotopes
Question
6 answers
It is apparently better to use a ceramic or porcelain drill instead of a metal drill bit to sample bone and teeth for oxygen stable isotope analysis because the metal could alter the d18O signal. Could someone explain why this is?
Relevant answer
Answer
Given the chemical make-up of ceramic / porcelain drill bits one would have thought it is the other way 'round. The only way I can think of a metal drill bit changing the 18O signature of bone or tooth bioapatite would be through heat stress (too much pressure being applied while drilling or drill set to too high a speed or both).  In all my work we have always used diamond-tipped drill bits in concjunction with a variable-speed dental drill.  If the correlation we got between bioapatite 18O and source water 18O is anything to go by, this combination of tools (and using a moderate drill speed) does not cause any 18O artefacts.  BTW, if you do not have a dental drill (with foot pedal for speed control) buy one; it is worth it.  However, do not purchase an NHS-for-human-dentistry approved model since they are beastly expensive. Look for a dental drill in veterinary supplies companies.  What they sell is exactly the same article (sometimes even from the same Swiss manufacturer) but at a fraction of the cost what NHS supplies companies charge.
  • asked a question related to Oxygen Isotopes
Question
5 answers
I would like to analyze volcanic glass samples on the TC/EA for their oxygen isotopic ratio, but am not sure of a good standard to use. Does anyone know of articles that delve into this, or standards that have been used in the past?
Relevant answer
Answer
You can consult www.ciaaw.org with plenty of guidelines and articles
  • asked a question related to Oxygen Isotopes
Question
7 answers
I feel we need to re evaluate this idea that we have been hearing since we were in high school!
Relevant answer
Answer
Well I found something that might of interest.
  • asked a question related to Oxygen Isotopes
Question
4 answers
For NMR experiments
Relevant answer
Answer
Quite a simple method for labelled 17 /18/O hyrogen peroxide synthesis is probably this one:
oxidize fine barium powder in a chamber at 500 oC in a stream of the selected oxygen isotope. The temperature should not exceed 700oC, due to decomposition of the peroxide. The reaction proceeds in two steps:
1/ 2 Ba + O2 = 2 BaO
2/ 2BaO + O2 = 2 BaO2
Prepared barium peroxide add slowly into H2SO4 /p.a./ and the following reaction will proceed: BaO2 + H2SO4 = H2O2 + BaSO4. I recommend you to cool the reaction mixture in an ice bath.
The labelled hydrogen peroxide will be obtained by vacuum destilation of arising
peroxide from the reaction mixture. The temperature of the water bath should not exceed 60 oC.
Note: 80 - 100 % hydrogen peroxide is relatively stabile endothermic compound even at elevated temperatures, however it explodes at temperatures close to its b.p.. Also, all glas materials /round bottom flask, condenser.../ must be absolutely clean, to avoid an accident.
If you do not need peroxide of high concentration use less concentrated H2SO4, maybe 60 % might do.