HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Doyle, A. Articles by Schimel, J. P. Search for Related Content PubMed Articles by Doyle, A. Articles by Schimel, J. P. Agricola Articles by Doyle, A. Articles by Schimel, J. P. Related Collections Soil Microbiology Nitrogen Soil Organic Matter Nutrient Cycling

DIVISION S-8—NUTRIENT MANAGEMENT & SOIL & PLANT ANALYSIS

Persulfate Digestion and Simultaneous Colorimetric Analysis of Carbon and Nitrogen in Soil Extracts

Dep. of Ecology, Evolution and Marine Biology, Univ. of California, Santa Barbara, CA 93106

^* Corresponding author (doyle{at}lifesci.ucsb.edu).

Persulfate digestions have been used for analyzing dissolved organic carbon (DOC) and nitrogen (DON), but most existing methods do not simultaneously analyze the same digest. Persulfate oxidizes DON to NO^–₃, and DOC to CO₂, which was trapped in the alkaline digest solution. We optimized the persulfate digestion for simultaneous analysis of dissolved CO₂ and NO^–₃ with flow injection analysis (FIA). Dissolved CO₂ was diffused across a Gore-Tex (W.L. Gore & Associates, Inc., Sunnyvale, CA) membrane and analyzed with a pH indicator, while NO^–₃ was analyzed with a standard Griess-Ilosvay reaction after Cd reduction. Digestions of glycine, urea, and yeast extract solutions recovered 97 to 99% of C and 92 to 96% of N, while digestions of lysine and nicotinimide recovered slightly less (93 to 94% C, 87 to 93% N). Glycine N, used as a digested standard to which sample recoveries were scaled, improved calculated recovery 94 to 103%. Dissolved organic C concentrations were not significantly different for persulfate oxidation (PO) and high temperature catalytic oxidation (HTCO) for 13 organic and mineral soil extracts with and without prior chloroform fumigation. Nitrogen recovery was higher for PO than HTCO. The DOC blanks were 0.5 to 1.0 mg C L^–1 and detection limit was 0.5 mg C L^–1, and both could be lowered if needed. The upper limit of analysis was at least 2000 mg C L^–1 with dilution. The digest was performed at temperatures as low as 80°C or as high as 125°C with equivalent results. We recommend the low temperature to reduce leakage. This analytical system is particularly convenient for the simultaneous analysis of microbial biomass C and N with the fumigation-extraction procedure.

Abbreviations: DIC, dissolved inorganic carbon • DOC, dissolved organic carbon • DON, dissolved organic nitrogen • DOP, dissolved organic phosphorus • FIA, flow injection analysis • HTCO, high temperature catalytic oxidation • LTER, long-term ecological research • PO, persulfate oxidation • TDC, total dissolved carbon • TDN, total dissolved nitrogen

This article has been cited by other articles:

				J. B. McKinlay, J. G. Zeikus, and C. Vieille Insights into Actinobacillus succinogenes Fermentative Metabolism in a Chemically Defined Growth Medium Appl. Envir. Microbiol., November 1, 2005; 71(11): 6651 - 6656. [Abstract] [Full Text] [PDF]