every place, person, and process leaves a molecular fingerprint it can't take back.
means a chemical signature is the unique combination of elements, isotopes, or compounds that identifies where something came from or what it's been through.
from grew out of 20th-century mass spectrometry and isotope geochemistry, when scientists realized atoms of the same element can have different masses, and those ratios record history like a receipt.
mars meteorites — oxygen isotope ratios matched viking lander atmosphere data, 1983
chernobyl fallout — cesium-137 signature tracked over europe for decades after 1986
ivory poaching busts — strontium isotopes pin elephant tusks to specific african regions
perfume counterfeits — gas chromatography exposes fake chanel by missing trace compounds