RESEARCH BASE
Search 3,721 documents across 34 fields — every claim tier-rated by evidence
3,633 are the core, quality-scored corpus (34 lettered sections — see How We Work); the remaining 88 are cross-corpus synthesis documents (68 InterDocs, 12 Connections, 8 Theories) also indexed here.
20 results for "nitrogen isotopes"
G_4_09 — Bioarchaeology and Forensic Anthropology: Reading the Dead
Bioarchaeology—the study of human remains from archaeological contexts—transforms skeletons from anonymous objects into biographical records of individual lives. Through stable isotope analysis of bone and tooth enamel,
G_1_04 — Isotope Analysis and Provenance Studies
Isotope analysis — the measurement of ratios of stable or radiogenic isotopes preserved in human bone, tooth enamel, animal remains, ceramics, metals, and organic residues — has become one of the most powerful tools in m
G_1_07 — Stable Isotope Analysis and Ancient Diets
Stable isotope analysis of human and animal remains — primarily the measurement of carbon ($\delta^{13}$C), nitrogen ($\delta^{15}$N), and sulfur ($\delta^{34}$S) isotope ratios in bone collagen, tooth enamel, hair kerat
ZF_1_16 — Paleoceanography and Foraminifera: Reconstructing Ancient Oceans from Microfossil Archives
Paleoceanography — the study of the history of the oceans and their role in Earth's climate system through geological time — relies fundamentally on the geochemical analysis of foraminifera (single-celled protists with c
ZF_2_07 — Marine Microbiology and Plankton
Marine microorganisms — bacteria, archaea, protists, viruses, and microscopic algae — constitute the invisible foundation of ocean life, driving global biogeochemical cycles, producing roughly half of the world's oxygen,
ZF_4_08 — Ocean Acidification Paleoclimate Record
Ocean acidification — the decrease in seawater pH caused by absorption of atmospheric CO₂ — is not only a modern phenomenon but has occurred repeatedly throughout Earth's history, leaving distinctive signals in the geolo
ZF_4_15 — Ocean Sediments: Deep-Sea Cores, Proxy Records, and Paleoclimate
Ocean sediments are the Earth's most comprehensive climate archive — a continuous record of planetary conditions extending back over 200 million years, slowly accumulated grain by grain on the deep seafloor at rates of m
ZF_4_14 — Harmful Algal Blooms: Red Tides, Toxins, and Eutrophication
Harmful algal blooms (HABs) — rapid proliferations of microscopic algae (phytoplankton) or cyanobacteria that produce toxins, deplete oxygen, or otherwise damage marine ecosystems, fisheries, and human health — are incre
Q_2_06 — Nucleosynthesis: How the Elements Were Forged
Every element in the periodic table has a specific cosmic origin story. Big Bang nucleosynthesis (BBN) produced hydrogen, helium, and traces of lithium in the first 20 minutes after the Big Bang. Stellar nucleosynthesis
Q_3_13 — Interstellar Objects: 'Oumuamua, Borisov, and Interstellar Visitors
Interstellar objects (ISOs) are bodies — asteroids, comets, or other macroscopic objects — that originate in other star systems and pass through our solar system on unbound, hyperbolic trajectories. While the theoretical
Q_3_17 — Titan: Prebiotic Chemistry on Saturn's Largest Moon
Titan, Saturn's largest moon (diameter 5,150 km — larger than Mercury), is the only body in the solar system besides Earth with stable surface liquids and a dense nitrogen-dominated atmosphere. Discovered by Christiaan H
ZB_3_21 — Soil Microbiome
The soil microbiome encompasses the entire community of microorganisms inhabiting soil — bacteria, archaea, fungi, protists, and viruses — constituting the most biodiverse ecosystem on Earth. [KEY FINDING] A single gram
ZB_3_09 — Mutualism and Cooperation in Nature
Mutualism — an interspecific interaction in which both partners benefit — is one of the most important ecological relationships on Earth, underpinning ecosystem function from coral reefs to forests to the human gut. The
ZB_3_12 — Soil Ecology: The Living Skin of the Earth
Soil — far from inert dirt — is the most biologically diverse habitat on Earth, containing an estimated 25–30% of all species on the planet. A single gram of healthy soil harbors approximately 1 billion bacteria (from 10
G_2_17 — Biogeochemistry and Ancient Environmental Reconstruction
Biogeochemistry — the study of chemical, physical, geological, and biological processes that govern the composition and cycling of elements and compounds in natural environments — provides essential tools for reconstruct
O_1_14 — Sprites, Elves, and Blue Jets: Upper Atmosphere Transient Luminous Events
Transient Luminous Events (TLEs) are a family of large-scale optical and electrical phenomena occurring in the upper atmosphere (stratosphere, mesosphere, and lower ionosphere, ~20-100 km altitude) above active thunderst
R_1_09 — The Great Oxidation Event: Oxygen, Cyanobacteria, and Earth's Atmospheric Transformation
The Great Oxidation Event (GOE), occurring approximately 2.4–2.1 billion years ago during the Paleoproterozoic, was the most dramatic chemical transformation in Earth's history — atmospheric oxygen rose from trace levels
S_1_21 — Quantum Sensors and Metrology
Quantum sensors exploit the extreme sensitivity of quantum systems — atoms, ions, photons, superconducting circuits, and spin defects — to measure physical quantities (time, frequency, magnetic and electric fields, gravi
F_2_06 — Tin Sources and the Bronze Age Mystery
The Bronze Age (c. 3300–1200 BCE) depended fundamentally on tin — the scarce metal alloyed with copper to produce bronze (typically 88–92% copper, 8–12% tin). While copper was widely available across the Mediterranean, N
ZA_4_19 — Cryogenics and Low-Temperature Physics
Cryogenics — the production and behavior of materials at temperatures below ~120 K (−153 °C) — began with Heike Kamerlingh Onnes (Leiden), who first liquefied helium on July 10, 1908, reaching 4.2 K and opening the ultra
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