Estimating modern carbon burial rates in lakes using a single sediment sample

William O. Hobbs, Daniel R. Engstrom, Shawn P. Scottler, Kyle D. Zimmer, James B. Cotner

Limnol. Oceanogr. Methods 11:316-326 (2013) | DOI: 10.4319/lom.2013.11.316

ABSTRACT: The rate of organic carbon (OC) burial in inland waters is an important flux in the global C-cycle. Here we provide methodological improvements that offer a rapid and accurate assessment of modern OC burial rates in lakes from a single surface-sediment sample. Using a 93 lake dataset of reliably dated sediment cores (OC burial of 9 to 318 g m-2 y-1), we demonstrate the applicability of this approach in a variety of lake types. We validate our estimated rates of OC burial against (1) measured whole-lake accumulation from the sum of multiple area-weighted sediment cores, (2) single central-basin cores adjusted for sediment focusing, and (3) duplicate sediment cores taken in multiple locations and at different times (4-10 years apart) in 9 lakes. Our single-sample estimates, which were in good agreement with measured values, suggest a within-lake variability of 4 g m-2 y-1 and have a small inter-lake error of only 6.5%. The applicability of this approach to other lakes and regions requires knowledge of (1) atmospheric 210Pb flux, (2) an estimate of supported 210Pb activity, and (3) some understanding of typical sedimentation rates in the study lakes. This approach provides an accurate assessment of OC burial, with increased potential for greater spatial coverage in inland waters and improved ability to address questions focused on terrestrialá¾¢aquatic exchanges of organic carbon.