{"thcode":2,"term":{"code":435,"name":"geochemical processes","parent":101,"scope":"Processes affecting the amount, distribution, or structure of chemical elements in air, water, soil, rocks, and minerals."},"uf":[],"bt":[{"code":101,"name":"biological and physical processes","parent":1174,"scope":"All continuing activities, functions, and phenomena associated with organisms and non-living matter."},{"code":1174,"name":"topics","parent":1,"scope":"Themes, subjects, and concerns for which USGS information resources are relevant."},{"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":1346,"name":"biodegradation","parent":435,"scope":"Reduction in the concentration of harmful chemicals by the action of animals and plants."},{"code":1731,"name":"carbon sequestration","parent":435,"scope":"Long-term storage of carbon in soils and terrestrial organic material, either by natural or engineered processes. Typically of importance for the balance of CO2 in the global climate system. "},{"code":2058,"name":"ocean acidification","parent":435,"scope":"Decrease in the pH of ocean waters as a result of the increase in atmospheric carbon dioxide concentration."},{"code":1703,"name":"ore formation","parent":435,"scope":"Geochemical processes resulting in concentration of useful chemical elements and compounds, in earth materials.  Typically refers to metal ores."},{"code":1708,"name":"oxidation and reduction","parent":435,"scope":"Addition or reduction of oxygen in a compound accompanied by exchange of electrons among atoms."},{"code":1711,"name":"reaction transport","parent":435,"scope":"Chemical reactions occurring during ground-water flow."},{"code":1715,"name":"sorption","parent":435,"scope":"Attachment of chemical substances to materials, either externally (by adsorption) or internally (by absorption)."},{"code":2279,"name":"thermal maturation","parent":435,"scope":"Chemical alteration of organic material within sediments and sedimentary rocks as a result of heat. Measures of thermal maturation indicate the extent of transformation of detrital organic material into coal and petroleum."}],"rt":[{"code":93,"name":"biogeochemical cycling","parent":310,"scope":"The cycling of chemical constituents through a biological system."},{"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."},{"code":1710,"name":"soil formation","parent":451,"scope":"Geological, geochemical, and ecological processes that work together to produce soils."}]}