{"thcode":2,"term":{"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."},"uf":[{"name":"light stable-isotope analysis","usewith":false},{"name":"stable isotope analysis","usewith":false}],"bt":[{"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":[{"code":86,"name":"beryllium isotope analysis","parent":654,"scope":"Method of age determination based on measurement of the activity of beryllium-10, used in dating deep-sea sediments, and in determining sedimentation rates."},{"code":142,"name":"carbon isotope analysis","parent":654,"scope":"Experimental determination of the proportion of a given stable carbon isotope (C12 or C13) in a sample."},{"code":855,"name":"oxygen isotope analysis","parent":654,"scope":"Experimental determination of the proportion of a given stable oxygen isotope in a sample."},{"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."}],"rt":[{"code":89,"name":"biochemistry","parent":650,"scope":"Study of chemical processes that occur within or are mediated by living organisms."},{"code":2278,"name":"environmental proxies","parent":734,"scope":"Biological, chemical, or physical features whose presence, characteristics, or behavior reflect environmental parameters of interest that cannot be readily or efficiently observed or measured directly."},{"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."}]}