Data for Evaluation of Nutrient, Alkalinity, and Acid Neutralizing Capacity Stabilities in Water Samples Analyzed by the National Water Quality Laboratory -- 2023-2024

The U.S. Geological Survey evaluated the stability of water-sample chemical analysis of nutrient, alkalinity, and acid neutralizing capacity constituents with respect to the duration between sample collection and laboratory analysis, also known as sample holding times. Included in this data release are results used to evaluate the stability of the chemical properties alkalinity (as calcium carbonate [CaCO3]), filtered; acid neutralizing capacity (as CaCO3), unfiltered; total ammonia (NH3) as nitrogen (N), filtered; total NH3 plus organic nitrogen as N, filtered and unfiltered; nitrite (NO2-) as N, filtered; nitrate (NO3-) plus NO2- as N, filtered; total N, filtered and unfiltered; orthophosphate (PO4-3) as phosphorous (P), filtered; and total P as P, (filtered and unfiltered) in water over holding times ranging between 2 and 180 days. In addition, graphs used for the study as well as blind sample results from the USGS Quality Systems Branch-Inorganic Blind Sample Project are included in this data release.