{"thcode":2,"term":{"code":1191,"name":"tritium analysis","parent":654,"scope":"Mass spectrometric measurement of the decay of the radioactive isotope of hydrogen in water samples as a means of dating and investigating changes in water."},"uf":[{"name":"tritium-helium dating","usewith":false}],"bt":[{"code":654,"name":"light stable isotope analysis","parent":609,"scope":"Analytical technique using mass spectrometry to measure the different isotopic forms of low mass (light) elements such as oxygen, hydrogen, carbon, nitrogen and sulfur that occur in samples."},{"code":609,"name":"isotopic analysis","parent":619,"scope":"Experimental determination of the proportion of a given isotope (or isotopes) in a sample."},{"code":619,"name":"laboratory methods","parent":734,"scope":"Techniques to analyze and test samples in a place equipped and designed for the work."},{"code":734,"name":"methods","parent":1,"scope":"Techniques, methods, procedures, or strategies for research, management, collection, or analysis of scientific information in USGS."},{"code":1,"name":"Categories","parent":null,"scope":"Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."}],"nt":[],"rt":[{"code":89,"name":"biochemistry","parent":650,"scope":"Study of chemical processes that occur within or are mediated by living organisms."},{"code":437,"name":"geochemistry","parent":291,"scope":"Study of the distribution of chemical elements and natural compounds on the earth and in the atmosphere and the chemical processes that affect the earth."}]}