14C as a tool to trace terrestrial carbon in a complex lake system: implications for foodweb structure and carbon cycling

Evelyn Keaveney, Paula Reimer, Christopher Barry, Robert Foy

Research output: Contribution to conferencePoster

Abstract

Carbon and nitrogen stable isotope analysis (SIA) has identified the terrestrial subsidy of freshwater food-webs but relies on different 13C fractionation in aquatic and terrestrial primary producers. However dissolved inorganic carbon (DIC) is partly comprised of 13C depleted respiration of terrestrial C and ‘old’ C derived from weathering of catchment geology. SIA thus fails to differentiate between the contribution of old and recently fixed terrestrial C. DIC in alkaline lakes is partially derived from weathering of 14C-free carbonaceous bedrock This
yields an artificial age offset leading samples to appear significantly older than their actual age. As such, 14C can be used as a biomarker to identify the proportion of autochthonous C in the food-web. With terrestrial C inputs likely to increase, the origin and utilisation of ‘old’ or ‘recent’ allochthonous C in the food-web can also be determined. Stable isotopes and 14C were measured for biota, particulate organic matter (POM), DIC and dissolved organic carbon (DOC) from Lough Erne, Northern Ireland, a humic but alkaline lake. High winter δ15N values in calanoid zooplankton (δ15N =24‰) relative to phytoplankton and POM (δ15N =6‰ and 12‰ respectively) may reflect several microbial trophic levels between terrestrial C and calanoids. Furthermore winter calanoid 14C ages are consistent with DOC from inflowing rivers (87 and 75 years BP respectively) but not phytoplankton (355 years BP). Summer calanoid δ13N, δ15N and 14C (312 years BP) indicate greater reliance on phytoplankton. There is also temporal and spatial variation in DIC, DOC and POM C isotopes.
LanguageEnglish
Publication statusPublished - 21 Aug 2012
Event12th International Paleolimnology Symposium - Glasgow, United Kingdom
Duration: 21 Aug 201424 Aug 2014

Conference

Conference12th International Paleolimnology Symposium
CountryUnited Kingdom
CityGlasgow
Period21/08/201424/08/2014

Fingerprint

dissolved inorganic carbon
particulate organic matter
dissolved organic carbon
food web
stable isotope
carbon
phytoplankton
lake
weathering
winter
nitrogen isotope
trophic level
biomarker
biota
bedrock
zooplankton
respiration
temporal variation
spatial variation
fractionation

Keywords

  • carbon-cycling
  • freshwater
  • food webs

Cite this

Keaveney, E., Reimer, P., Barry, C., & Foy, R. (2012). 14C as a tool to trace terrestrial carbon in a complex lake system: implications for foodweb structure and carbon cycling. Poster session presented at 12th International Paleolimnology Symposium, Glasgow, United Kingdom.
Keaveney, Evelyn ; Reimer, Paula ; Barry, Christopher ; Foy, Robert . / 14C as a tool to trace terrestrial carbon in a complex lake system: implications for foodweb structure and carbon cycling. Poster session presented at 12th International Paleolimnology Symposium, Glasgow, United Kingdom.
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abstract = "Carbon and nitrogen stable isotope analysis (SIA) has identified the terrestrial subsidy of freshwater food-webs but relies on different 13C fractionation in aquatic and terrestrial primary producers. However dissolved inorganic carbon (DIC) is partly comprised of 13C depleted respiration of terrestrial C and ‘old’ C derived from weathering of catchment geology. SIA thus fails to differentiate between the contribution of old and recently fixed terrestrial C. DIC in alkaline lakes is partially derived from weathering of 14C-free carbonaceous bedrock Thisyields an artificial age offset leading samples to appear significantly older than their actual age. As such, 14C can be used as a biomarker to identify the proportion of autochthonous C in the food-web. With terrestrial C inputs likely to increase, the origin and utilisation of ‘old’ or ‘recent’ allochthonous C in the food-web can also be determined. Stable isotopes and 14C were measured for biota, particulate organic matter (POM), DIC and dissolved organic carbon (DOC) from Lough Erne, Northern Ireland, a humic but alkaline lake. High winter δ15N values in calanoid zooplankton (δ15N =24‰) relative to phytoplankton and POM (δ15N =6‰ and 12‰ respectively) may reflect several microbial trophic levels between terrestrial C and calanoids. Furthermore winter calanoid 14C ages are consistent with DOC from inflowing rivers (87 and 75 years BP respectively) but not phytoplankton (355 years BP). Summer calanoid δ13N, δ15N and 14C (312 years BP) indicate greater reliance on phytoplankton. There is also temporal and spatial variation in DIC, DOC and POM C isotopes.",
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author = "Evelyn Keaveney and Paula Reimer and Christopher Barry and Robert Foy",
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note = "12th International Paleolimnology Symposium ; Conference date: 21-08-2014 Through 24-08-2014",

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Keaveney, E, Reimer, P, Barry, C & Foy, R 2012, '14C as a tool to trace terrestrial carbon in a complex lake system: implications for foodweb structure and carbon cycling' 12th International Paleolimnology Symposium, Glasgow, United Kingdom, 21/08/2014 - 24/08/2014, .

14C as a tool to trace terrestrial carbon in a complex lake system: implications for foodweb structure and carbon cycling. / Keaveney, Evelyn; Reimer, Paula; Barry, Christopher; Foy, Robert .

2012. Poster session presented at 12th International Paleolimnology Symposium, Glasgow, United Kingdom.

Research output: Contribution to conferencePoster

TY - CONF

T1 - 14C as a tool to trace terrestrial carbon in a complex lake system: implications for foodweb structure and carbon cycling

AU - Keaveney, Evelyn

AU - Reimer, Paula

AU - Barry, Christopher

AU - Foy, Robert

PY - 2012/8/21

Y1 - 2012/8/21

N2 - Carbon and nitrogen stable isotope analysis (SIA) has identified the terrestrial subsidy of freshwater food-webs but relies on different 13C fractionation in aquatic and terrestrial primary producers. However dissolved inorganic carbon (DIC) is partly comprised of 13C depleted respiration of terrestrial C and ‘old’ C derived from weathering of catchment geology. SIA thus fails to differentiate between the contribution of old and recently fixed terrestrial C. DIC in alkaline lakes is partially derived from weathering of 14C-free carbonaceous bedrock Thisyields an artificial age offset leading samples to appear significantly older than their actual age. As such, 14C can be used as a biomarker to identify the proportion of autochthonous C in the food-web. With terrestrial C inputs likely to increase, the origin and utilisation of ‘old’ or ‘recent’ allochthonous C in the food-web can also be determined. Stable isotopes and 14C were measured for biota, particulate organic matter (POM), DIC and dissolved organic carbon (DOC) from Lough Erne, Northern Ireland, a humic but alkaline lake. High winter δ15N values in calanoid zooplankton (δ15N =24‰) relative to phytoplankton and POM (δ15N =6‰ and 12‰ respectively) may reflect several microbial trophic levels between terrestrial C and calanoids. Furthermore winter calanoid 14C ages are consistent with DOC from inflowing rivers (87 and 75 years BP respectively) but not phytoplankton (355 years BP). Summer calanoid δ13N, δ15N and 14C (312 years BP) indicate greater reliance on phytoplankton. There is also temporal and spatial variation in DIC, DOC and POM C isotopes.

AB - Carbon and nitrogen stable isotope analysis (SIA) has identified the terrestrial subsidy of freshwater food-webs but relies on different 13C fractionation in aquatic and terrestrial primary producers. However dissolved inorganic carbon (DIC) is partly comprised of 13C depleted respiration of terrestrial C and ‘old’ C derived from weathering of catchment geology. SIA thus fails to differentiate between the contribution of old and recently fixed terrestrial C. DIC in alkaline lakes is partially derived from weathering of 14C-free carbonaceous bedrock Thisyields an artificial age offset leading samples to appear significantly older than their actual age. As such, 14C can be used as a biomarker to identify the proportion of autochthonous C in the food-web. With terrestrial C inputs likely to increase, the origin and utilisation of ‘old’ or ‘recent’ allochthonous C in the food-web can also be determined. Stable isotopes and 14C were measured for biota, particulate organic matter (POM), DIC and dissolved organic carbon (DOC) from Lough Erne, Northern Ireland, a humic but alkaline lake. High winter δ15N values in calanoid zooplankton (δ15N =24‰) relative to phytoplankton and POM (δ15N =6‰ and 12‰ respectively) may reflect several microbial trophic levels between terrestrial C and calanoids. Furthermore winter calanoid 14C ages are consistent with DOC from inflowing rivers (87 and 75 years BP respectively) but not phytoplankton (355 years BP). Summer calanoid δ13N, δ15N and 14C (312 years BP) indicate greater reliance on phytoplankton. There is also temporal and spatial variation in DIC, DOC and POM C isotopes.

KW - carbon-cycling

KW - freshwater

KW - food webs

M3 - Poster

ER -

Keaveney E, Reimer P, Barry C, Foy R. 14C as a tool to trace terrestrial carbon in a complex lake system: implications for foodweb structure and carbon cycling. 2012. Poster session presented at 12th International Paleolimnology Symposium, Glasgow, United Kingdom.