Journal
CHEMICAL GEOLOGY
Volume 282, Issue 3-4, Pages 67-83Publisher
ELSEVIER
DOI: 10.1016/j.chemgeo.2011.01.007
Keywords
delta C-13; C/N ratio; Organic Matter; Acid Treatment; Method Comparison; Environmental Reconstruction
Categories
Funding
- NERC [NE/F007264/1]
- NERC [bgs04003, nigl010001] Funding Source: UKRI
- Natural Environment Research Council [nigl010001, bgs04003] Funding Source: researchfish
Ask authors/readers for more resources
This study is the first systematic comparison of the effect of acid treatment methods on the reliability of organic carbon [C] and nitrogen [N], and carbon isotope (delta C-13) values on a range of terrestrial and aquatic, modern and geological environmental materials. We investigated the 3 most common methods; (i) acidification followed by sequential deionised water rinses (rinse method); (ii) acidification in silver capsules (capsule method); and (iii) acidification by exposure to an acid vapour (fumigation method). We also investigated the effect of sample size and capsule type (silver and tin) on C/N ratio and delta C-13 values. We find (i) that %C, %N, C/N and delta C-13 showed significant within and between method variability; (ii) disproportionate and non-linear offsets of %C, %N and C/N values after acidification within and between methods and within and between sample materials; (iii) that alterations in %C did not necessarily manifest themselves in shifts in delta C-13, and vice-versa; (iv) that small (similar to 90 mu g C) sample sizes showed consistent overestimations and inaccuracies after acidification; (v) that the effect of capsule type was not significant on most samples, but did show a notable effect on our aquatic materials, generally increasing %C and %N, and producing depleted delta C-13 values. These findings raise cause for concern on the interpretative nature of C/N ratios and their support for carbon isotope values. The comparability between laboratories (different preparation methods) and environmental settings (amount, type and nature of OM) is also likely to be problematic. We conclude that the response of C and N concentrations in organic matter to acid treatment in environmental materials is neither negligible nor systematic. (C) 2011 Elsevier B.V. All rights reserved.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available