Abstract
Researchers frequently must store water samples >24 h after collection until chemical analyses can be accomplished. Samples are commonly stored in darkness at near-freezing temperatures until analysis, but effects of this storage method on soil water chemistry are not well-documented. Soil water samples were collected from eastern hemlock [Tsuga canadensis (L.) Carriere] stands and analyzed initially and over time to determine if nitrate (NC
3
-
), chloride (Cl
-
), sulfate (SO
4
2-
), ammonium (NH
4
+
), and/or total nitrogen (TN) concentrations changed when samples were stored in darkness at 2-4°C. Subsamples were analyzed <24 h after collection and reanalyzed five times in a 12 to 24 wk period following sample collection. Nitrate concentrations remained stable for at least one wk and were only slightly lower than initial concentrations after 3-16 wk of storage. Chloride and SO
4
2-
remained stable for 16 wk, while TN remained stable for 8 wk and decreased slightly after 24 wk. Most NH
4
+
concentrations were below the limit of quantification, but concentrations of samples with quantifiable NH
4
+
decreased in the first week of storage. Overall, cold storage in darkness was effective for preserving NO
3
-
, Cl
-
, SO
4
2-
, and TN concentrations in soil water, but NH
4
+
analyses should probably be performed as soon as possible after sample collection.