Description: High‑frequency nitrate sensors, paired with streamflow data, improve load estimates but can differ from laboratory measurements. Analysis of about 2,400 paired samples in Iowa showed a small, statistically significant positive bias of 0.20 mg/L, varying by site and season. A statistical experiment tested whether this bias affects annual load estimates.

Author: Jennifer Murphy

Author Bio: Jenny Murphy is a research hydrologist at the US Geological Survey Central Midwest Water Science Center specializing in water-quality trend and load analysis in rivers and stream. Jenny has been with the Survey for 15 years and prior to that completed her graduate work at Vanderbilt University.