Carbon and nitrogen isotope variations in sedimenting organic matter in Lake Lugano

Bernasconi, Stefano M.; Barbieri, Alberto; Simona, Marco

doi:10.4319/lo.1997.42.8.1755

Cited by 116 publications

(106 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…␦ 13 C carb and ␦ 13 C org record: Trophic state or artefact of hydrological change?-The ␦ 13 C composition of carbonate and OM in sediments have been extensively used to evaluate long-term changes in trophic state and C cycling due to nutrient loading (Meyers and Ishawitari 1995;Bernasconi et al 1997;Hodell and Schelske 1998) or land-use change (Brenner et al 1999;Herczeg et al 2001). In addition to changes in water residence time discussed above, there has been increased loading of nitrates to Blue Lake as a consequence of increased inflow of the high NO groundwater Ϫ 3 (Lamontagne 2002).…”

Section: Impact Of Increased Through-flow On Dic Cycling-mentioning

confidence: 99%

A modern isotope record of changes in water and carbon budgets in a groundwater‐fed lake: Blue Lake, South Australia

Herczeg

Leaney

Dighton

et al. 2003

Limnology & Oceanography

View full text Add to dashboard Cite

Groundwater is often a major component of lake water and chemical balances. Alteration in catchment subsurface water balances through land-use change and pumping can affect lake biogeochemical cycles through changes in groundwater flow rates. We present a modern (ϳ200 yr) sediment isotope record (␦ 18 O carb , ␦ 13 C carb , and ␦ 13 C org ) of changes to the water and carbon budget of Blue Lake, which is situated in karstic limestone in South Australia and is mostly fed by groundwater. The 3.5‰ decrease in ␦ 18 O carb and ␦ 13 C carb deposited in lake sediments since ϳ1850 reflects higher rates of groundwater through-flow due to rainfall variability, land-use change, and increased rates of pumping over the past 40 yr. Calculated water residence times, based on the isotopic data, were 23 Ϯ 2 yr before 1850 and decreased by the late twentieth century to 8 Ϯ 2 yr. Concomitant dissolved inorganic carbon (DIC) residence times were 3.8 and 2.2 yr, respectively. Although burial rates of CaCO 3 have increased by about threefold over the past 40 yr, there is no evidence that substantial changes in organic carbon deposition has occurred. The shorter DIC residence time is largely due to increased input and higher CO 2 evasion rates. About 88% of C carb and ϳ96% of C org generated within the water column is remineralized, but the isotopic composition is essentially unaltered in the sediments. The measured variations in ␦ 13 C carb and ␦ 13 C org of sediments are thought to reflect changes to DIC residence time and increased CO 2 (aq) concentrations rather than changes in lake productivity.

show abstract

Section: Impact Of Increased Through-flow On Dic Cycling-mentioning

confidence: 99%

A modern isotope record of changes in water and carbon budgets in a groundwater‐fed lake: Blue Lake, South Australia

Herczeg

Leaney

Dighton

et al. 2003

Limnology & Oceanography

View full text Add to dashboard Cite

show abstract

“…This was exemplified for phytoplankton as well as for terrestrial fresh plant material which tend to have lighter values than biotically processed matter as soil organic matter (Adams and Sterner. 2000;Bernasconi et al. 1997;Fuentes.…”

Section: Differences In Sedimentation Patterns Between Sitesmentioning

confidence: 99%

“…2010;Owens and Law. 1989) or "aged" phytoplankton detritus (Bernasconi et al. 1997; Van der Nat et al.…”

Section: Differences In Sedimentation Patterns Between Sitesmentioning

confidence: 99%

Allochthonous contribution to seasonal and spatial variability of organic matter sedimentation in a deep oligotrophic lake (Lake Constance)

Fuentes¹,

Güde²,

Wessels³

et al. 2013

Limnologica

View full text Add to dashboard Cite

“…Such a relatively large variability might be explained by the lack of taxonomic control in our analyses, since the ephippia might originate from different species of Daphnia. Alternatively, these cladocerans might feed on algae in different parts of the water column, or the range of ephippial d 13 C might represent seasonal changes in the carbon isotopic signature of particulate organic matter in the water column (Bernasconi et al 1997). Irrespective of the cause for the larger spread in Daphnia d 13 C, the carbon isotopic composition of these cladoceran remains indicate that benthic and planktonic organisms in Slotseng fed on food items with a similar carbon isotopic composition, with no evidence that methanogenic carbon played an important role for macroinvertebrates in this lake ecosystem.…”

Section: Culturing Experimentsmentioning

confidence: 99%

Fossil chironomid δ13C as a proxy for past methanogenic contribution to benthic food webs in lakes?

et al. 2009

View full text Add to dashboard Cite

We used a series of experiments to determine whether stable carbon isotope analysis of modern and fossil larval head capsules of chironomids allowed identification of their dietary carbon source. Our main focus was to assess whether carbon from naturally 13 C-depleted methane-oxidizing bacteria (MOB) can be traced in chironomid cuticles using stable carbon isotope analysis. We first showed that a minimum sample weight of *20 lg was required for our equipment to determine head capsule d 13 C with a standard deviation of 0.5%. Such a small minimum sample weight allows taxon-specific d 13 C analyses at a precision sufficient to differentiate whether head capsules consist mainly of carbon derived from MOB or from other food sources commonly encountered in lake ecosystems. We then tested the effect of different chemical pre-treatments that are commonly used for sediment processing on d 13 C measurements on head capsules. Processing with 10% KOH (2 h), 10% HCl (2 h), or 40% HF (18 h) showed no detectable effect on d 13 C, whereas a combination of boiling, accelerated solvent extraction and heavy chemical oxidation resulted in a small (0.2%) but statistically significant decrease in d 13 C values. Using culturing experiments with MOB grown on 13 C-labelled methane, we demonstrated that methanogenic carbon is transferred not only into the larval tissue, but also into chironomid head capsules. Taxon-specific d 13 C of fossil chironomid head capsules from different lake sediments was analyzed. d 13 C of head capsules generally ranged from -28 to -25.8%, but in some instances we observed d 13 C values as low as -36.9 to -31.5%, suggesting that carbon from MOB is traceable in fossil and subfossil chironomid remains. We demonstrate that stable carbon isotope analyses of fossil chironomid head capsules can give insights into dietary links and carbon cycling in benthic food webs in the past and that the method has the potential to reconstruct the importance of MOB in the palaeo-diet of chironomid larvae and, indirectly, to infer past changes in methane flux at the sediment water interface in lakes.

show abstract

Carbon and nitrogen isotope variations in sedimenting organic matter in Lake Lugano

Cited by 116 publications

References 21 publications

A modern isotope record of changes in water and carbon budgets in a groundwater‐fed lake: Blue Lake, South Australia

A modern isotope record of changes in water and carbon budgets in a groundwater‐fed lake: Blue Lake, South Australia

Allochthonous contribution to seasonal and spatial variability of organic matter sedimentation in a deep oligotrophic lake (Lake Constance)

Fossil chironomid δ13C as a proxy for past methanogenic contribution to benthic food webs in lakes?

Contact Info

Product

Resources

About