MEPS 287:251-253 (2005)  -  doi:10.3354/meps287251

Stable isotope food web studies: a case for standardized sample treatment

Ute Jacob*, Katja Mintenbeck, Thomas Brey, Rainer Knust, Kerstin Beyer

Alfred Wegener Institute for Polar and Marine Research, PO Box 120161, 27515 Bremerhaven, Germany

ABSTRACT: Enrichment of the stable isotopes 13C and 15N across trophic levels is a commonly used tool in studies on organic matter flow and food webs. However, there is still no accepted standard for pre-analysis sample preparation. Thus, potential methodological bias in single studies may hamper comparability and scalability of data from different sources. Sample CaCO3 content introduces a positive bias in δ13C measurements and a negative bias in δ15N measurements. The acidification of samples to remove inorganic carbonate significantly reduces both δ13C and δ15N. As a standard procedure we recommend (1) acidifying samples with as little hydrochloric acid (HCl) as possible using the drop-by-drop technique, and (2) restraining from rinsing after HCl application.


KEY WORDS: Isotope signatures · Carbonates · Sample acidification


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