Hydrochemistry Protocols


In use from 1996-01-01


The following chemical variables are measured on filtered water (0.45 micron) unless noted: Ca, Mg, Na, K, nitrate, total alkalinity (unfiltered water), chloride, sulfate, ammonium, soluble reactive phosphorus (PO4-P), total dissolved phosphorus (TDP), dissolved organic carbon (DOC), dissolved Si, and specific conductance (Cond; uS/cm corrected to 25 degrees C). In some cases conductance is measured in the field (Cond-Field) as well as later in the lab (Cond-Lab).

Beginning in August 2006 dissolved Ca, Mg, Na and K were measured by ion chromatography (IC) instead of flame atomic absorption spectrophotometry (AA). Data source is distinguished as, for example, Ca-AA and Ca-IC. Overlapping analyses showed comparable results from the two methods.

The pH is measured in the field. Additional field measurements include water temperature and dissolved oxygen as percent and mg/l. For pumped groundwater sampled from wells, these measurements are taken in an overflowing container.
For the LTER streams, additional lab measurements include total suspended solids and total phosphorus (TP). Stream discharge is measured at a nearby site on Augusta Creek by the USGS.

See the following references for methods:

Hamilton, S.K., J.L. Tank, D.F. Raikow, W.M. Wollheim, B.J. Peterson, and J.R. Webster. 2001. Nitrogen uptake and transformation in a midwestern US stream: A stable isotope enrichment study. Biogeochemistry 54(3): 297-340.

Hamilton, S.K., A.L. Kurzman, C. Arango, L. Jin, and G.P. Robertson. 2007. Evidence for carbon sequestration by agricultural liming. Global Biogeochemical Cycles 21, GB2021, doi:10.1029/2006GB002738.

Hamilton, S.K., D.A. Bruesewitz, G.P. Horst, and O. Sarnelle. 2009. Biogenic calcite-phosphorus precipitation as a negative feedback to lake eutrophication. Canadian Journal of Fisheries and Aquatic Sciences 66(2): 343-50.