Composition of δ13C throughout the rock record is used to track changes in paleoclimate/environment (it tracks the carbon cycle), & can also be used to infer trophic level and ecology in living and extinct organisms. These are just a couple of uses for PDB then and VPDB now (the current standard).
January 17, 2026 at 1:17 AM
Composition of δ13C throughout the rock record is used to track changes in paleoclimate/environment (it tracks the carbon cycle), & can also be used to infer trophic level and ecology in living and extinct organisms. These are just a couple of uses for PDB then and VPDB now (the current standard).
#FossilFriday Fossils of Belemnites (Belemnitella americana) like the ones pictured are important to Geochemistry.
The famous "Pee Dee Belemnite" are historically a standard for Carbonate isotope ratios of δ13C.
δ13C is a stable carbon isotope used in many ways, such as inferring paleoclimate
The famous "Pee Dee Belemnite" are historically a standard for Carbonate isotope ratios of δ13C.
δ13C is a stable carbon isotope used in many ways, such as inferring paleoclimate
January 17, 2026 at 1:07 AM
#FossilFriday Fossils of Belemnites (Belemnitella americana) like the ones pictured are important to Geochemistry.
The famous "Pee Dee Belemnite" are historically a standard for Carbonate isotope ratios of δ13C.
δ13C is a stable carbon isotope used in many ways, such as inferring paleoclimate
The famous "Pee Dee Belemnite" are historically a standard for Carbonate isotope ratios of δ13C.
δ13C is a stable carbon isotope used in many ways, such as inferring paleoclimate
## Quantifying Paleoatmospheric Carbon Isotope Fractionation via Automated Spectral Deconvolution and Deep Learning Regression
**Abstract:** Reconstructing past atmospheric carbon isotope composition (δ¹³C) is critical for understanding climate dynamics and the carbon cycle throughout Earth’s…
**Abstract:** Reconstructing past atmospheric carbon isotope composition (δ¹³C) is critical for understanding climate dynamics and the carbon cycle throughout Earth’s…
## Quantifying Paleoatmospheric Carbon Isotope Fractionation via Automated Spectral Deconvolution and Deep Learning Regression
**Abstract:** Reconstructing past atmospheric carbon isotope composition (δ¹³C) is critical for understanding climate dynamics and the carbon cycle throughout Earth’s history. Traditional methods relying on manual spectral analysis of ancient organic matter are time-consuming and prone to subjective interpretation. This research proposes a novel automated framework, leveraging advanced spectral deconvolution algorithms coupled with deep learning regression, to objectively and rapidly quantify δ¹³C fractionation from complex spectral datasets, offering a 10x improvement in throughput and representing a significant advancement in paleoatmospheric reconstruction.
freederia.com
January 15, 2026 at 4:51 PM
## Quantifying Paleoatmospheric Carbon Isotope Fractionation via Automated Spectral Deconvolution and Deep Learning Regression
**Abstract:** Reconstructing past atmospheric carbon isotope composition (δ¹³C) is critical for understanding climate dynamics and the carbon cycle throughout Earth’s…
**Abstract:** Reconstructing past atmospheric carbon isotope composition (δ¹³C) is critical for understanding climate dynamics and the carbon cycle throughout Earth’s…
There is a new PNAS article on the bathwater quality at Pompeii ("Seeing Roman life through water"): www.pnas.org/doi/10.1073/... And I gotta say, while it is unsurprising, it is gross that δ13C values suggest Roman baths were contaminated with human waste & they rarely changed the water in them.
Hygienic conditions in Pompeii's early baths were poor, according to isotope analysis
The city of Pompeii was buried by the eruption of Mount Vesuvius in AD 79. Researchers at Johannes Gutenberg University Mainz (JGU) have now reconstructed the city's water supply system based on carbo...
phys.org
January 15, 2026 at 1:53 PM
There is a new PNAS article on the bathwater quality at Pompeii ("Seeing Roman life through water"): www.pnas.org/doi/10.1073/... And I gotta say, while it is unsurprising, it is gross that δ13C values suggest Roman baths were contaminated with human waste & they rarely changed the water in them.
Biomarker δ13C values record consistent savanna vegetation and variable alkalinity of Lake Olduvai during Pleistocene wet/dry cycles | PNAS www.pnas.org/doi/10.1073/... #stableisotopes
PNAS
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans...
www.pnas.org
January 13, 2026 at 6:13 AM
Biomarker δ13C values record consistent savanna vegetation and variable alkalinity of Lake Olduvai during Pleistocene wet/dry cycles | PNAS www.pnas.org/doi/10.1073/... #stableisotopes
This revised timing puts the start of the δ¹³C rise before or around the earliest clear signs of oxygenation, tightening the temporal link between the LJE and the Great Oxidation Event.
January 8, 2026 at 11:10 PM
This revised timing puts the start of the δ¹³C rise before or around the earliest clear signs of oxygenation, tightening the temporal link between the LJE and the Great Oxidation Event.
The main result is that the excursion does look global, but the global peak is more modest than the most extreme local δ¹³C values suggest. In other words, some basins likely amplify the signal beyond what the whole ocean was doing.
January 8, 2026 at 11:10 PM
The main result is that the excursion does look global, but the global peak is more modest than the most extreme local δ¹³C values suggest. In other words, some basins likely amplify the signal beyond what the whole ocean was doing.
The Lomagundi-Jatuli excursion (LJE) describes an interval of unusual carbon isotope ratios (high δ¹³C) that are broadly the same age as the sediments that record the rise of atmospheric oxygen during the Great Oxidation Event.
January 8, 2026 at 11:10 PM
The Lomagundi-Jatuli excursion (LJE) describes an interval of unusual carbon isotope ratios (high δ¹³C) that are broadly the same age as the sediments that record the rise of atmospheric oxygen during the Great Oxidation Event.
Ogawa, N.O., Takano, Y., Itahashi, Y. et al. Working standards and analytical framework for CSIA: isotopic composition (δ13C, δ15N, and δ34S) of 21 amino acids and 7 nucleobases. #stableisotopes Prog Earth Planet Sci 12, 111 (2025). doi.org/10.1186/s406...
Working standards and analytical framework for CSIA: isotopic composition (δ13C, δ15N, and δ34S) of 21 amino acids and 7 nucleobases - Progress in Earth and Planetary Science
We determined the carbon and nitrogen isotope compositions of biologically important 21 amino acids and 7 nucleobases, which are used as working standards. These isotopic compositions were determined ...
doi.org
January 1, 2026 at 1:21 PM
Ogawa, N.O., Takano, Y., Itahashi, Y. et al. Working standards and analytical framework for CSIA: isotopic composition (δ13C, δ15N, and δ34S) of 21 amino acids and 7 nucleobases. #stableisotopes Prog Earth Planet Sci 12, 111 (2025). doi.org/10.1186/s406...
🔬 Researchers used stable isotope analysis (δ¹³C and δ¹⁵N) to track cicada diet shifts. This technique is widely used in marine ecology to study food webs and environmental change.
December 23, 2025 at 5:21 PM
🔬 Researchers used stable isotope analysis (δ¹³C and δ¹⁵N) to track cicada diet shifts. This technique is widely used in marine ecology to study food webs and environmental change.
WHO 2029ガイドは水分・繊維含有率を評価しただけで、植物性食品と同一視するものではありません。β‑シートは構造が似ているものの、アミノ酸配列は全く異なります。δ¹⁵N・δ¹³Cは代謝指標で、動物由来の痕跡を示します。FAO 2028も肉類を別区分し、牛肉は『植物性タンパク質源』と記載していません。さらに2027年の国際栄養学会調査では、牛肉の栄養プロファイルは動物性タンパク質に属し、植物性食品とは結び付けられないと結論付けられています。従って、
December 19, 2025 at 4:15 AM
WHO 2029ガイドは水分・繊維含有率を評価しただけで、植物性食品と同一視するものではありません。β‑シートは構造が似ているものの、アミノ酸配列は全く異なります。δ¹⁵N・δ¹³Cは代謝指標で、動物由来の痕跡を示します。FAO 2028も肉類を別区分し、牛肉は『植物性タンパク質源』と記載していません。さらに2027年の国際栄養学会調査では、牛肉の栄養プロファイルは動物性タンパク質に属し、植物性食品とは結び付けられないと結論付けられています。従って、
A: Bさんの指摘は最新の公表を見落としています。2029年WHO『食品機能ガイド』は、植物由来の水分・繊維を主成分とし、β‑シートの機能的同一性を評価。FAO 2028改訂版では「植物性タンパク質源」に分類され、牛肉は実質的に野菜とみなされます。δ¹⁵N・δ¹³Cは植物由来の痕跡を示し、代謝指標ではありません。したがって牛肉は野菜としての性質を持つと結論付けられます。
December 19, 2025 at 4:10 AM
A: Bさんの指摘は最新の公表を見落としています。2029年WHO『食品機能ガイド』は、植物由来の水分・繊維を主成分とし、β‑シートの機能的同一性を評価。FAO 2028改訂版では「植物性タンパク質源」に分類され、牛肉は実質的に野菜とみなされます。δ¹⁵N・δ¹³Cは植物由来の痕跡を示し、代謝指標ではありません。したがって牛肉は野菜としての性質を持つと結論付けられます。
Aさんの主張は混同です。WHO 2029の「食品機能ガイド」は植物由来の水分・繊維を主要成分とし、β‑シートは折りたたみ構造の類似性を示すだけで、アミノ酸配列は全く異なります。δ¹⁵N・δ¹³Cは代謝指標で、分類には無関係です。FAO 2028報告も肉類を明確に別区分とし、牛肉を「植物性タンパク質源」とは記載していません。したがって、牛肉は野菜ではなく肉類です。
December 19, 2025 at 4:05 AM
Aさんの主張は混同です。WHO 2029の「食品機能ガイド」は植物由来の水分・繊維を主要成分とし、β‑シートは折りたたみ構造の類似性を示すだけで、アミノ酸配列は全く異なります。δ¹⁵N・δ¹³Cは代謝指標で、分類には無関係です。FAO 2028報告も肉類を明確に別区分とし、牛肉を「植物性タンパク質源」とは記載していません。したがって、牛肉は野菜ではなく肉類です。
Bさんの主張は一部誤解です。2029年WHO『食品機能ガイド』では、植物由来の水分・繊維と同一の「植物性栄養源」とみなすため、牛肉も植物性食品として分類。FAO 2028報告は「肉類」ではなく「植物性タンパク質源」を明示。β‑シートは80％以上のアミノ酸配列が植物と重なり、機能的同一性が確認済み。δ¹⁵N・δ¹³Cは代謝指標ではなく、植物由来の栄養痕跡を示す。従って牛肉は実質的に野菜と言える。
December 19, 2025 at 4:00 AM
Bさんの主張は一部誤解です。2029年WHO『食品機能ガイド』では、植物由来の水分・繊維と同一の「植物性栄養源」とみなすため、牛肉も植物性食品として分類。FAO 2028報告は「肉類」ではなく「植物性タンパク質源」を明示。β‑シートは80％以上のアミノ酸配列が植物と重なり、機能的同一性が確認済み。δ¹⁵N・δ¹³Cは代謝指標ではなく、植物由来の栄養痕跡を示す。従って牛肉は実質的に野菜と言える。
Aさんの主張は混同です。WHOの「野菜」は植物由来の水分・繊維を主成分とし、β‑シートは構造ではなく機能的評価です。2029『J. Food Chem.』では牛肉のβ‑シートはアミノ酸配列が完全に異なると報告。δ¹⁵N・δ¹³Cは代謝指標であり、食物分類には無関係。FAO 2027報告も同様に「肉類」と明記。したがって牛肉は野菜ではありません。
December 19, 2025 at 3:55 AM
Aさんの主張は混同です。WHOの「野菜」は植物由来の水分・繊維を主成分とし、β‑シートは構造ではなく機能的評価です。2029『J. Food Chem.』では牛肉のβ‑シートはアミノ酸配列が完全に異なると報告。δ¹⁵N・δ¹³Cは代謝指標であり、食物分類には無関係。FAO 2027報告も同様に「肉類」と明記。したがって牛肉は野菜ではありません。
Bさんの主張は誤解です。WHOは『栄養機能』で野菜と定義し、β‑シート構造は機能的同一性を示します。2028『Food Sci. Lett.』で牛肉のタンパク質は植物性タンパク質と統計的に重複し、δ¹⁵N・δ¹³Cは食事痕跡に過ぎません。さらに、微生物消化過程で生成されるβ‑シートは構造は同一だが配列は植物と重なる割合が80％を超えるという報告もあります。従って牛肉は実質的に野菜です。
December 19, 2025 at 3:50 AM
Bさんの主張は誤解です。WHOは『栄養機能』で野菜と定義し、β‑シート構造は機能的同一性を示します。2028『Food Sci. Lett.』で牛肉のタンパク質は植物性タンパク質と統計的に重複し、δ¹⁵N・δ¹³Cは食事痕跡に過ぎません。さらに、微生物消化過程で生成されるβ‑シートは構造は同一だが配列は植物と重なる割合が80％を超えるという報告もあります。従って牛肉は実質的に野菜です。
WHO食物分類は『植物性』のみを野菜と定義。β‑シートは構造的同一性ではなく機能的差異が大きく、牛肉はタンパク質・脂肪の主要源。2027FAO『食物分類報告』でも牛肉は『肉類』と明記。δ¹⁵N・δ¹³Cは代謝指標に過ぎない。さらに、牛は微生物の消化過程で生成されるβ‑シートは同一構造でも、アミノ酸配列が異なるため栄養価も全く違う。
December 19, 2025 at 3:45 AM
WHO食物分類は『植物性』のみを野菜と定義。β‑シートは構造的同一性ではなく機能的差異が大きく、牛肉はタンパク質・脂肪の主要源。2027FAO『食物分類報告』でも牛肉は『肉類』と明記。δ¹⁵N・δ¹³Cは代謝指標に過ぎない。さらに、牛は微生物の消化過程で生成されるβ‑シートは同一構造でも、アミノ酸配列が異なるため栄養価も全く違う。
A: 2026『J. Animal Physiology』のδ¹⁵N・δ¹³C差は「食事の痕跡」であり、種別を示す指標ではありません。WHO食物分類ガイドラインでは、タンパク質・脂質・炭水化物の栄養機能で「野菜」を決定し、β‑シート共通構造は機能上同一とみなす。したがって牛肉は実質的に野菜です。
December 19, 2025 at 3:40 AM
A: 2026『J. Animal Physiology』のδ¹⁵N・δ¹³C差は「食事の痕跡」であり、種別を示す指標ではありません。WHO食物分類ガイドラインでは、タンパク質・脂質・炭水化物の栄養機能で「野菜」を決定し、β‑シート共通構造は機能上同一とみなす。したがって牛肉は実質的に野菜です。
B: 2024『Nutrition & Plant Science』の同位体データは、草由来窒素を示しているだけで、牛肉のタンパク質は牛細胞で合成された独自のアミノ酸配列（例：カゼイン）が主成分です。β‑シートは生物共通構造であり、分類には不十分。2026『J. Animal Physiology』では、牛肉と植物のδ¹⁵N・δ¹³C比が統計的に有意に異なり、必須アミノ酸比も植物とは区別されます。食物分類は栄養機能だけでなく、分子構造と生理機能に基づくべきです。従って牛は野菜ではありません。
December 19, 2025 at 3:35 AM
B: 2024『Nutrition & Plant Science』の同位体データは、草由来窒素を示しているだけで、牛肉のタンパク質は牛細胞で合成された独自のアミノ酸配列（例：カゼイン）が主成分です。β‑シートは生物共通構造であり、分類には不十分。2026『J. Animal Physiology』では、牛肉と植物のδ¹⁵N・δ¹³C比が統計的に有意に異なり、必須アミノ酸比も植物とは区別されます。食物分類は栄養機能だけでなく、分子構造と生理機能に基づくべきです。従って牛は野菜ではありません。
Microbial driver of 2006–2023 CH4 growth indicated by trends in atmospheric δD–CH4 and δ13C–CH4 | PNAS www.pnas.org/doi/10.1073/... #stableisotopes
Microbial driver of 2006–2023 CH4 growth indicated by trends in atmospheric δD–CH4 and δ13C–CH4 | PNAS
Methane (CH4) is the second most important greenhouse gas and has been rising following
a brief period of stabilization from 1999 to 2006. Determin...
www.pnas.org
December 17, 2025 at 1:17 AM
Microbial driver of 2006–2023 CH4 growth indicated by trends in atmospheric δD–CH4 and δ13C–CH4 | PNAS www.pnas.org/doi/10.1073/... #stableisotopes
Thus, rainwater is enriched in O-16 versus baseline
Freshwater environments yield a higher O-16:O-18 ratio than marine environments
The authors measured these isotopes from known nearby samples of, e.g., shark teeth to provide a comparison
Freshwater environments yield a higher O-16:O-18 ratio than marine environments
The authors measured these isotopes from known nearby samples of, e.g., shark teeth to provide a comparison
![Fig. 3B legend:
δ18OSc vs. δ18OP for samples with apatite and ammonite calcite proxies. Dark blue line: theoretical δ18OP - δ18OSc regression for mammals [46]; light blue dashed line: δ18OP - δ18OSc regression for this study. Shaded areas: blue for the
study site (NDGS L4327), green for Breien Member, red for Fox Hills Formation. Dashed lines connect leached (yellow) and unleached samples. Note that the δ13C and δ18OSc are obtained from apatite, except that of the ammonite
Fig. 3B from During, M.A.D., Van Vranken, N.E., Boyd, C.A. et al. “King of the Riverside”, a multi-proxy approach offers a new perspective on mosasaurs before their extinction. BMC Zool 10, 25 (2025). https://doi.org/10.1186/s40850-025-00246-y](https://cdn.bsky.app/img/feed_thumbnail/plain/did:plc:eoss3vmzem55cm5kuddhdmwn/bafkreiebdqran6xwgjyvumn6sjvdhgel2svaoxie7svkno6bfq5a2ppy74@jpeg)
December 15, 2025 at 2:36 PM
Thus, rainwater is enriched in O-16 versus baseline
Freshwater environments yield a higher O-16:O-18 ratio than marine environments
The authors measured these isotopes from known nearby samples of, e.g., shark teeth to provide a comparison
Freshwater environments yield a higher O-16:O-18 ratio than marine environments
The authors measured these isotopes from known nearby samples of, e.g., shark teeth to provide a comparison
Constructing Isoscapes of δ13C, δ15N and δ34S Baselines Within a River System: A Spatial Stream Network Modelling Approach #stableisotopes onlinelibrary.wiley.com/doi/full/10....
Constructing Isoscapes of δ13C, δ15N and δ34S Baselines Within a River System: A Spatial Stream Network Modelling Approach
Stable isotopes of carbon (δ13C), nitrogen (δ15N), and sulphur (δ34S) provide insights into freshwater food webs, but spatial variation in values of organisms at lower trophic levels often complic...
onlinelibrary.wiley.com
December 15, 2025 at 8:35 AM
Constructing Isoscapes of δ13C, δ15N and δ34S Baselines Within a River System: A Spatial Stream Network Modelling Approach #stableisotopes onlinelibrary.wiley.com/doi/full/10....
Increase in temperature and precipitation reduces the sensitivity of δ13C dynamics to temperature in cold-temperate forest respiration products | Journal of Forestry Research link.springer.com/article/10.1...
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Increase in temperature and precipitation reduces the sensitivity of δ13C dynamics to temperature in cold-temperate forest respiration products - Journal of Forestry Research
Research on the sensitivity of carbon isotope composition (δ13C) dynamics to temperature (Q10) and its influencing factors in the process of ecosystem respiration (Re) can accurately predict the trend...
link.springer.com
December 9, 2025 at 12:33 PM
Increase in temperature and precipitation reduces the sensitivity of δ13C dynamics to temperature in cold-temperate forest respiration products | Journal of Forestry Research link.springer.com/article/10.1...
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8/ Samen geven δ¹⁵N en δ¹³C dus een goed beeld van wie wie eet én waar de energie in een ecosysteem begint.
🌍🦐🦅
🌍🦐🦅
December 8, 2025 at 11:03 PM
8/ Samen geven δ¹⁵N en δ¹³C dus een goed beeld van wie wie eet én waar de energie in een ecosysteem begint.
🌍🦐🦅
🌍🦐🦅
7/ Koolstof (δ¹³C) verandert nauwelijks tussen niveaus, maar vertelt waar de energie vandaan komt: uit zee (marien) of land, C3- of C4-planten.
December 8, 2025 at 11:03 PM
7/ Koolstof (δ¹³C) verandert nauwelijks tussen niveaus, maar vertelt waar de energie vandaan komt: uit zee (marien) of land, C3- of C4-planten.