Video Experimental Relacionado
Updated: Jul 11, 2026
11:19
Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses
Published on: October 21, 2016
Registro isotópico de carbono estable de 500,000 años en el agujero del diablo, Nevada
Science (New York, N.Y.)
|January 21, 1994
Resumen
Las variaciones de carbono-13 en la calcita de Devils Hole revelan cambios climáticos pasados. Estos registros de isótopos de carbono se correlacionan con las terminaciones glaciales, lo que sugiere cambios en el dióxido de carbono atmosférico y la densidad de la vegetación.
Área de la Ciencia:
- Paleoclimatología Paleoclimatología
- La geoquímica es la geoquímica.
- La hidrología isotópica es la hidrología de isótopos.
Sus antecedentes:
- El núcleo de calcita del Devils Hole (DH-11) proporciona un valioso archivo de las condiciones ambientales pasadas.
- Comprender la variabilidad climática pasada es crucial para predecir el cambio climático futuro.
Objetivo del estudio:
- Para analizar las variaciones del carbono-13 (delta) en el núcleo de calcita DH-11.
- Para investigar la relación entre las proporciones de isótopos del delta (((13) C y el oxígeno en el núcleo.
- Para interpretar las implicaciones paleoambientales de las fluctuaciones del delta observadas.
Principales métodos:
- Análisis del carbono-13 (delta) en calcita venosa del núcleo DH-11.
- Comparación de las series temporales delta ((13) C con los datos de isótopos de oxígeno.
- Modelado de fuentes potenciales de variaciones del delta.
Principales resultados:
- Se identificaron cuatro mínimos prominentes del delta 13C cerca de las terminaciones glaciares V a II.
- La serie temporal delta ((13) C está inversamente correlacionada con el registro de isótopos de oxígeno, lo que la lleva hasta 7000 años.
- Estas variaciones probablemente reflejan cambios en el delta ((13) C del agua de recarga de acuíferos.
Conclusiones:
- El registro del delta puede indicar cambios globales de CO2 atmosférico o cambios regionales en la vegetación en el sur de la Gran Cuenca.
- Los mínimos en el registro del delta corresponden a períodos de máxima extensión y densidad de vegetación.
- El mecanismo de transporte de estas señales isotópicas a Devils Hole sin alteración significativa sigue siendo una pregunta abierta.
Videos de Conceptos Relacionados
01:12Isotopes
Elements have a set number of protons that determines their atomic number (Z). For example, all atoms with eight protons are oxygen; however, the number of neutrons can vary for atoms of the same element. The sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are called isotopes. Elements can have multiple isotopes, for example, carbon-12, carbon-13, and carbon-14.An element's atomic mass, or weight, is a...
01:50Global Climate Change
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
03:18Nuclear Stability
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together in the...
To hold positively charged protons together in the...
02:48Radioactive Decay and Radiometric Dating
Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. The number of disintegrations per unit time is called the activity (A), which is directly proportional to the number of nuclei in the sample. The decay constant (λ) is an average probability of decay per nucleus in unit time.
01:10Carbon-13 (¹³C) NMR: Overview
Carbon-13 is a naturally occurring NMR-active isotope of carbon with a low natural abundance of 1.1%. In contrast, carbon-12 is the most abundant isotope of carbon with zero nuclear spin. Therefore, it is NMR inactive. The gyromagnetic ratio of carbon-13 is smaller than that of protons. As a result, carbon-13 resonance is about 6000 times weaker than proton resonance. For a given magnetic field strength, the resonance frequency of carbon-13 is about one-fourth of the resonance frequency for...