@article { ISI:000290678100009, title = {Radiocarbon and stable carbon isotopic insights into provenance and cycling of carbon in Lake Superior}, journal = {LIMNOLOGY AND OCEANOGRAPHY}, volume = {56}, number = {{3}}, year = {2011}, month = {MAY}, pages = {867-886}, type = {Article}, abstract = {This study applies radiocarbon and stable carbon isotopic distributions to investigate carbon sources and cycling within Lake Superior. We report the radiocarbon (Delta C-14) and stable carbon isotope (delta C-13) values and the carbon concentrations within dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the lake{\textquoteright}s western basin water column. Samples were taken during spring mixing and late-summer thermal stratification over a 2-yr period (2007-2009). Distinct processes operating in the surface (photosynthesis) and deep waters (sediment resuspension and pore-water intrusion) control the relative contribution of modern and ancient DOC and POC in the water column. The terrigenous carbon input to the open lake POC varied from 13\% +/- 4\% during late summer stratification to 9\% +/- 3\% during spring mixing, with most of the terrestrial carbon being C-14-enriched (modern). The DIC reservoir cycles rapidly, with a bulk Delta C-14(DIC) value that records atmospheric radiocarbon levels from 3 yr prior to sampling. The DOC pool recycles on a longer time scale than does the DIC, with a DOC residence time of <= 60 yr. The suspended POC was in most cases older than co-occurring DOC, most likely as a result of resuspension of lake sediments.}, issn = {0024-3590}, doi = {10.4319/lo.2011.56.3.0867}, author = {Zigah, Prosper K. and Minor, Elizabeth C. and Werne, Josef P. and McCallister, S. Leigh} }