The Benthic Nepheloid Layer (BNL) North of the Keweenaw Peninsula in Lake Superior: Composition, Dynamics, and Role in Sediment Transport

Urban, Noel R.; Jeong, Jaebong; Chai, Yingtao

doi:10.1016/s0380-1330(04)70382-2

Cited by 16 publications

(16 citation statements)

References 38 publications

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“…Concentration trends of DOC, POC, PON, and DICThe somewhat higher DOC and POC concentrations at the nearshore site (BR) relative to the offshore site (OL) in May or June are due most likely to a combination of allochthonous OM inputs, the effects of terrestrially derived nutrient loading on autochthonous primary productivity (Urban et al 2005), and the effects of nearshore increases in water temperature on productivity.…”

Section: Discussionmentioning

confidence: 99%

“…These rapid declines in the largest OC pool in the lake are very intriguing and are likely driven by within-lake biogeochemical processes rather than lake water-level changes. They could be a key reason for the imbalanced carbon budgets reported by Cotner et al (2004) and Urban et al (2005), since the DOC pool is likely to be poorly constrained by snapshot data.…”

Section: Discussionmentioning

confidence: 99%

“…Potential causes of this include (1) a reduction in the rate of exchange between water-column DIC and atmospheric CO 2 during periods (April and November; Urban et al 2005) when the lake is supersaturated with pCO 2 and effluxes CO 2 to the atmosphere instead of taking in atmospheric 14 CO 2 (Abbott and Stanfford 1996), (2) a reduction in exchange between lake DIC and atmospheric 14 CO 2 during winter ice cover (December to May), and (3) a relatively long residence time of lake DIC. We determined the residence time to be , 3 yr (calculated using the DIC pool, , 125 Tg C, divided by a lake-atmospheric CO 2 exchange flux, The similarity in decline rate of D 14 C POC , and D 14 C DIC values in the surface waters during stratified conditions, in conjunction with our C : N data, and d 13 C trends for both POC and DIC imply that much of the POC in the stratified surface waters is derived from recent photosynthesis in the lake.…”

Section: Date Of Sample Collectionmentioning

confidence: 99%

“…As a result of their proximity to terrestrial environments and the associated delivery of allochthonous organic carbon (OC), inland aquatic systems can function simultaneously as both sinks and sources of atmospheric CO 2 (Cole et al 2007). Multiple biogeochemical processes, such as carbonate buffering, heterotrophic respiration, and sedimentary sequestration of OC, allow inland aquatic systems such as Lake Superior to outgas CO 2 to the atmosphere while concurrently burying OC at depth (Kritzberg et al 2005;Urban et al 2005). The bioavailability and cycling of carbon is also important in within-ecosystem processes, as inorganic carbon is a basic building block for autotrophy and because labile OC provides necessary carbon and energy sources for heterotrophy.…”

mentioning

confidence: 99%

“…Lake Superior is the Earth's largest freshwater lake by surface area (8.2 3 10 10 m 2 ), with maximum and mean depths of, respectively, 406 m and 150 m (Urban et al 2005). The lake is biogeochemically similar to open-ocean locations as a result of its oligotrophic nature, low terrestrial nutrient loading, and the dominance of its microbial food web on carbon cycling (Cotner et al 2004).…”

mentioning

confidence: 99%

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Radiocarbon and stable carbon isotopic insights into provenance and cycling of carbon in Lake Superior

Zigah

Minor

Werne

et al. 2011

Limnology & Oceanography

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This study applies radiocarbon and stable carbon isotopic distributions to investigate carbon sources and cycling within Lake Superior. We report the radiocarbon (D 14 C) and stable carbon isotope (d 13 C) values and the carbon concentrations within dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the lake's western basin water column. Samples were taken during spring mixing and late-summer thermal stratification over a 2-yr period (2007)(2008)(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% 6 4% during late summer stratification to 9% 6 3% during spring mixing, with most of the terrestrial carbon being 14 C-enriched (modern). The DIC reservoir cycles rapidly, with a bulk D 14 C 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.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%