Chang, C. C. U.S.G.S, ccchang@usgs.gov
Riggs, M. C. Carlos Avery Wildlife Center, riggs001@tc.umn.edu
Campbell, D. U.S.G.S., dhcampbe@usgs.gov
Silva, S. U.S.G.S., srsilva@usgs.gov
Kendall, C. U.S.G.S, ckendall@usgs.gov

 
NITRATE COLLECTION FOR N-15 AND O-18 ANALYSIS IN DILUTE WATERS
 
A method for collecting and recovering NO3 for N-15 and O-18 analysis from low ionic strength waters with modest dissolved organic carbon (DOC)concentrations (1-10 ppm) and low NO3 concentrations (1-10 micromole) is described. The method uses ion exchange columns, accommodates the large volumes of water (7-70l) required due to low NO3 concentration, and minimizes DOC accumulation. An earlier method resulted in lengthy loading times exceeding 24 hours. DOC often clogged the anion column and competed for NO3 sites. These problems were solved by a)prefiltering the sample c) using a courser resin, enabling more rapid sample flow, c) increasing the volume of resin, and d) putting a cation column in front of the anion column to protonate DOC, making it less likely to adhere to the anion column. This method can be done on site with minimum field equipment.
 
Day: Wednesday, Feb. 3
Time: Poster
Location: Sweeney Center
 
Code: SS50WE0292S