Colorimetric determination of nitrate plus nitrite in water by enzymatic reduction, automated discrete analyzer methods

Quantifying watershed‐scale groundwater loading and in‐stream fate of nitrate using high‐frequency water quality data

“…Samples were filtered and stored at 48C until analyzed at the USGS National Water Quality Laboratory for major ions and for nitrate plus nitrite using the enzymatic reduction method [Patton and Kryskalla, 2011]. A regression of depth and width-integrated discrete nitrate plus nitrite concentrations with sensor nitrate concentrations on 11-22 dates shows that the two were strongly correlated (r 2 5 0.97-0.99) across a range of flow conditions at all three sites (Figure 2).…”

Design and methods of the Southeast Stream Quality Assessment (SESQA), 2014

“…Current-use pesticides were analyzed in filtered water samples by the NWQL using a DAI LC-MS/MS (appendix 2, table 2-3; Sandstrom and others, in press). Samples for nutrients and major ions were analyzed by the NWQL as specified in appendix 2 (tables 2-1, 2-2) and described in Fishman andFriedman (1989), Fishman (1993), Patton and Kryskalla, (2003), and Patton and Kryskalla (2011). Total phosphorus (TP) concentrations were determined by colorimetry according to EPA method 365.1 (O'Dell, 1993).…”

“…Dissolved ammonia, nitrite, and orthophosphate colorimetric analyses are described by Fishman (1993). Dissolved nitrate-plus-nitrite concentrations were determined by low-level enzyme reduction colorimetry using an automated discrete analyzer, as described by Patton and Kryskalla (2011). Concentrations of dissolved cations were determined by inductively coupled plasma-atomic emission spectroscopy (ICP/AES) (Fishman, 1993), and concentrations of dissolved anions were determined by ion chromatography, as described by Fishman and Friedman (1989).…”

Chuckwalla Valley multiple-well monitoring site, Chuckwalla Valley, Riverside County

“…Analyses were performed by the USGS National Water Quality Laboratory in Lakewood, Colorado, and the USGS Stable Isotope Laboratory in Reston, Virginia, by following standard methods outlined by Fishman and Friedman (1989); Coplen and others (1991); Truitt (1992, 2000); Brenton and Arnett (1993);Fishman (1993); Coplen (1994); Struzeski and others (1996); Garbarino (1999); Garbarino and others (2006); and Patton and Kryskalla (2011). Carbon-13 and carbon-14 analyses were performed by Woods Hole Oceanographic Institute under contract with the USGS using standard methods described by Vogel and others (1987) and Donahue and others (1990).…”