Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Combining sources in stable isotope mixing models: alternative methods

Combining sources in stable isotope mixing models: alternative methods Stable isotope mixing models are often used to quantify source contributions to a mixture. Examples include pollution source identification; trophic web studies; analysis of water sources for soils, plants; or water bodies, and many others. A common problem is having too many sources to allow a unique solution. We discuss two alternative procedures for addressing this problem. One option is a priori to combine sources with similar signatures so the number of sources is small enough to provide a unique solution. Aggregation should be considered only when isotopic signatures of clustered sources are not significantly different, and sources are related so the combined source group has some functional significance. For example, in a food web analysis, lumping several species within a trophic guild allows more interpretable results than lumping disparate food sources, even if they have similar isotopic signatures. One result of combining mixing model sources is increased uncertainty of the combined end-member isotopic signatures and consequently the source contribution estimates; this effect can be quantified using the IsoError model ( http://www.epa.gov/wed/pages/models/isotopes/isoerror1_04.htm ). As an alternative to lumping sources before a mixing analysis, the IsoSource mixing model ( http://www.epa.gov/wed/pages/models/isosource/isosource.htm ) can be used to find all feasible solutions of source contributions consistent with isotopic mass balance. While ranges of feasible contributions for each individual source can often be quite broad, contributions from functionally related groups of sources can be summed a posteriori, producing a range of solutions for the aggregate source that may be considerably narrower. A paleohuman dietary analysis example illustrates this method, which involves a terrestrial meat food source, a combination of three terrestrial plant foods, and a combination of three marine foods. In this case, a posteriori aggregation of sources allowed strong conclusions about temporal shifts in marine versus terrestrial diets that would not have otherwise been discerned. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Oecologia Springer Journals

Combining sources in stable isotope mixing models: alternative methods

Phillips, Donald; Newsome, Seth; Gregg, Jillian
Oecologia , Volume 144 (4) – Feb 16, 2005
Download PDF
8 pages

Loading next page...
 
/lp/springer-journals/combining-sources-in-stable-isotope-mixing-models-alternative-methods-WzzoQECA5R

References (26)

Publisher
Springer Journals
Copyright
Copyright © 2005 by U.S. Government
Subject
Life Sciences; Plant Sciences ; Ecology
ISSN
0029-8549
eISSN
1432-1939
DOI
10.1007/s00442-004-1816-8
pmid
15711995
Publisher site
See Article on Publisher Site

Abstract

Stable isotope mixing models are often used to quantify source contributions to a mixture. Examples include pollution source identification; trophic web studies; analysis of water sources for soils, plants; or water bodies, and many others. A common problem is having too many sources to allow a unique solution. We discuss two alternative procedures for addressing this problem. One option is a priori to combine sources with similar signatures so the number of sources is small enough to provide a unique solution. Aggregation should be considered only when isotopic signatures of clustered sources are not significantly different, and sources are related so the combined source group has some functional significance. For example, in a food web analysis, lumping several species within a trophic guild allows more interpretable results than lumping disparate food sources, even if they have similar isotopic signatures. One result of combining mixing model sources is increased uncertainty of the combined end-member isotopic signatures and consequently the source contribution estimates; this effect can be quantified using the IsoError model ( http://www.epa.gov/wed/pages/models/isotopes/isoerror1_04.htm ). As an alternative to lumping sources before a mixing analysis, the IsoSource mixing model ( http://www.epa.gov/wed/pages/models/isosource/isosource.htm ) can be used to find all feasible solutions of source contributions consistent with isotopic mass balance. While ranges of feasible contributions for each individual source can often be quite broad, contributions from functionally related groups of sources can be summed a posteriori, producing a range of solutions for the aggregate source that may be considerably narrower. A paleohuman dietary analysis example illustrates this method, which involves a terrestrial meat food source, a combination of three terrestrial plant foods, and a combination of three marine foods. In this case, a posteriori aggregation of sources allowed strong conclusions about temporal shifts in marine versus terrestrial diets that would not have otherwise been discerned.

Journal

Oecologia – Springer Journals

Published: Feb 16, 2005

There are no references for this article.