https://cdn.earthdata.nasa.gov/conduit/upload/5182/KeywordsCommunityGuide_Baseline_v1_SIGNED_FINAL.pdf 23.6 2026-03-19T10:41:57.720Z https://gcmd.earthdata.nasa.gov/KeywordViewer/scheme/sciencekeywords/14625f2a-4186-4377-a0d9-88998bb6b775 pH Date=2018-03-07 User Id=tstevens Entity=Definition Operation=UPDATE Field=text System Note=update Definition Old Value=A measure of the alkaline or acid strength of a substance. pH is defined as the logarithm of the reciprocal of the hydrogen ion concentration of a solution. New Value=A measure of the alkaline or acid strength of a substance. pH is defined as the logarithm of the reciprocal of the hydrogen ion concentration of a solution. Date=2018-03-07 User Id=tstevens Entity=BroaderRelation Operation=DELETE User Note=Move Concepts System Note=delete broader relation Old Value=PH [14625f2a-4186-4377-a0d9-88998bb6b775,85923] - WATER QUALITY/WATER CHEMISTRY [8c02f5d1-ce86-4bf5-84d5-b3496cdba6ad,83565] Date=2018-03-12 User Id=tstevens Entity=Definition Operation=UPDATE Field=text System Note=update Definition Old Value=A measure of the alkaline or acid strength of a substance. pH is defined as the logarithm of the reciprocal of the hydrogen ion concentration of a solution. New Value=A measure of the alkaline or acid strength of a substance. pH is defined as the logarithm of the reciprocal of the hydrogen ion concentration of a solution. Date=2018-03-07 User Id=tstevens Entity=PrefLabel Operation=UPDATE Field=text System Note=update PrefLabel Old Value=PH New Value=pH Date=2018-03-07 User Id=tstevens Entity=Definition Operation=UPDATE Field=reference System Note=update Definition Old Value=Adapted from: Porteous, A. 1996. Dictionary of Environmental Science and Technology, Second Edition. John Wiley and Sons. p. 413. New Value=Adapted from: Porteous, A. 1996. Dictionary of Environmental Science and Technology, Second Edition. John Wiley and Sons. p. 413. Date=2018-03-07 User Id=tstevens Entity=BroaderRelation Operation=INSERT User Note=Move Concepts System Note=add broader relation New Value=PH [14625f2a-4186-4377-a0d9-88998bb6b775,85923] - WATER CHARACTERISTICS [f7e97dc3-1181-41b5-8b90-946eb2504110,310633] A measure of the alkaline or acid strength of a substance. pH is defined as the logarithm of the reciprocal of the hydrogen ion concentration of a solution. 2018-03-12 10:23:34.0