Carolina Olid

Carolina Olid
(Assistant professor)

Email: carolina.olid.garcia@slu.se

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Research Summary

My primary research goals are directed towards evaluating human and climate impact on ecological and biogeochemical processes using radionuclides as tracers. I have expertise in both terrestrial and aquatic ecosystems at various temporal and spatial scales. I am interested on climate change in boreal and arctic ecosystems where I model elemental (carbon, metals, nutrients) fluxes within soils, peatlands and lakes and their response to environmental stressors such as increasing temperatures or pollutants deposition.

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Current Projects

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Photos From the Field

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Carolina Olid’s Publications

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  2022 (1)

Groundwater discharge as a driver of methane emissions from Arctic lakes. Olid, C.; Rodellas, V.; Rocher-Ros, G.; Garcia-Orellana, J.; Diego-Feliu, M.; Alorda-Kleinglass, A.; Bastviken, D.; and Karlsson, J. Nature Communications, 13(1): 3667. June 2022. Number: 1 Publisher: Nature Publishing Group
Paper   doi   link   bibtex   abstract  

@article{olid_groundwater_2022,
	title = {Groundwater discharge as a driver of methane emissions from {Arctic} lakes},
	volume = {13},
	copyright = {2022 The Author(s)},
	issn = {2041-1723},
	url = {https://www.nature.com/articles/s41467-022-31219-1},
	doi = {10.1038/s41467-022-31219-1},
	abstract = {Lateral CH4 inputs to Arctic lakes through groundwater discharge could be substantial and constitute an important pathway that links CH4 production in thawing permafrost to atmospheric emissions via lakes. Yet, groundwater CH4 inputs and associated drivers are hitherto poorly constrained because their dynamics and spatial variability are largely unknown. Here, we unravel the important role and drivers of groundwater discharge for CH4 emissions from Arctic lakes. Spatial patterns across lakes suggest groundwater inflows are primarily related to lake depth and wetland cover. Groundwater CH4 inputs to lakes are higher in summer than in autumn and are influenced by hydrological (groundwater recharge) and biological drivers (CH4 production). This information on the spatial and temporal patterns on groundwater discharge at high northern latitudes is critical for predicting lake CH4 emissions in the warming Arctic, as rising temperatures, increasing precipitation, and permafrost thawing may further exacerbate groundwater CH4 inputs to lakes.},
	language = {en},
	number = {1},
	urldate = {2023-07-20},
	journal = {Nature Communications},
	author = {Olid, Carolina and Rodellas, Valentí and Rocher-Ros, Gerard and Garcia-Orellana, Jordi and Diego-Feliu, Marc and Alorda-Kleinglass, Aaron and Bastviken, David and Karlsson, Jan},
	month = jun,
	year = {2022},
	note = {Number: 1
Publisher: Nature Publishing Group},
	keywords = {\#nosource, Carbon cycle, Climate-change impacts},
	pages = {3667},
}

Lateral CH4 inputs to Arctic lakes through groundwater discharge could be substantial and constitute an important pathway that links CH4 production in thawing permafrost to atmospheric emissions via lakes. Yet, groundwater CH4 inputs and associated drivers are hitherto poorly constrained because their dynamics and spatial variability are largely unknown. Here, we unravel the important role and drivers of groundwater discharge for CH4 emissions from Arctic lakes. Spatial patterns across lakes suggest groundwater inflows are primarily related to lake depth and wetland cover. Groundwater CH4 inputs to lakes are higher in summer than in autumn and are influenced by hydrological (groundwater recharge) and biological drivers (CH4 production). This information on the spatial and temporal patterns on groundwater discharge at high northern latitudes is critical for predicting lake CH4 emissions in the warming Arctic, as rising temperatures, increasing precipitation, and permafrost thawing may further exacerbate groundwater CH4 inputs to lakes.

  2021 (2)

Global CO2 fertilization of Sphagnum peat mosses via suppression of photorespiration during the twentieth century. Serk, H.; Nilsson, M. B.; Bohlin, E.; Ehlers, I.; Wieloch, T.; Olid, C.; Grover, S.; Kalbitz, K.; Limpens, J.; Moore, T.; Münchberger, W.; Talbot, J.; Wang, X.; Knorr, K.; Pancotto, V.; and Schleucher, J. Scientific Reports, 11(1): 24517. December 2021. Bandiera_abtest: a Cc_license_type: cc_by Cg_type: Nature Research Journals Number: 1 Primary_atype: Research Publisher: Nature Publishing Group Subject_term: Biochemistry;Biogeochemistry;Biophysics;Chemical biology;Climate sciences;Ecology;Environmental sciences;Plant sciences Subject_term_id: biochemistry;biogeochemistry;biophysics;chemical-biology;climate-sciences;ecology;environmental-sciences;plant-sciences
Paper   doi   link   bibtex   abstract  

@article{serk_global_2021,
	title = {Global {CO2} fertilization of {Sphagnum} peat mosses via suppression of photorespiration during the twentieth century},
	volume = {11},
	copyright = {2021 The Author(s)},
	issn = {2045-2322},
	url = {https://www.nature.com/articles/s41598-021-02953-1},
	doi = {10.1038/s41598-021-02953-1},
	abstract = {Natural peatlands contribute significantly to global carbon sequestration and storage of biomass, most of which derives from Sphagnum peat mosses. Atmospheric CO2 levels have increased dramatically during the twentieth century, from 280 to {\textgreater} 400 ppm, which has affected plant carbon dynamics. Net carbon assimilation is strongly reduced by photorespiration, a process that depends on the CO2 to O2 ratio. Here we investigate the response of the photorespiration to photosynthesis ratio in Sphagnum mosses to recent CO2 increases by comparing deuterium isotopomers of historical and contemporary Sphagnum tissues collected from 36 peat cores from five continents. Rising CO2 levels generally suppressed photorespiration relative to photosynthesis but the magnitude of suppression depended on the current water table depth. By estimating the changes in water table depth, temperature, and precipitation during the twentieth century, we excluded potential effects of these climate parameters on the observed isotopomer responses. Further, we showed that the photorespiration to photosynthesis ratio varied between Sphagnum subgenera, indicating differences in their photosynthetic capacity. The global suppression of photorespiration in Sphagnum suggests an increased net primary production potential in response to the ongoing rise in atmospheric CO2, in particular for mire structures with intermediate water table depths.},
	language = {en},
	number = {1},
	urldate = {2022-01-20},
	journal = {Scientific Reports},
	author = {Serk, Henrik and Nilsson, Mats B. and Bohlin, Elisabet and Ehlers, Ina and Wieloch, Thomas and Olid, Carolina and Grover, Samantha and Kalbitz, Karsten and Limpens, Juul and Moore, Tim and Münchberger, Wiebke and Talbot, Julie and Wang, Xianwei and Knorr, Klaus-Holger and Pancotto, Verónica and Schleucher, Jürgen},
	month = dec,
	year = {2021},
	note = {Bandiera\_abtest: a
Cc\_license\_type: cc\_by
Cg\_type: Nature Research Journals
Number: 1
Primary\_atype: Research
Publisher: Nature Publishing Group
Subject\_term: Biochemistry;Biogeochemistry;Biophysics;Chemical biology;Climate sciences;Ecology;Environmental sciences;Plant sciences
Subject\_term\_id: biochemistry;biogeochemistry;biophysics;chemical-biology;climate-sciences;ecology;environmental-sciences;plant-sciences},
	keywords = {\#nosource, Biochemistry, Biogeochemistry, Biophysics, Chemical biology, Climate sciences, Ecology, Environmental sciences, Plant sciences},
	pages = {24517},
}

Natural peatlands contribute significantly to global carbon sequestration and storage of biomass, most of which derives from Sphagnum peat mosses. Atmospheric CO2 levels have increased dramatically during the twentieth century, from 280 to \textgreater 400 ppm, which has affected plant carbon dynamics. Net carbon assimilation is strongly reduced by photorespiration, a process that depends on the CO2 to O2 ratio. Here we investigate the response of the photorespiration to photosynthesis ratio in Sphagnum mosses to recent CO2 increases by comparing deuterium isotopomers of historical and contemporary Sphagnum tissues collected from 36 peat cores from five continents. Rising CO2 levels generally suppressed photorespiration relative to photosynthesis but the magnitude of suppression depended on the current water table depth. By estimating the changes in water table depth, temperature, and precipitation during the twentieth century, we excluded potential effects of these climate parameters on the observed isotopomer responses. Further, we showed that the photorespiration to photosynthesis ratio varied between Sphagnum subgenera, indicating differences in their photosynthetic capacity. The global suppression of photorespiration in Sphagnum suggests an increased net primary production potential in response to the ongoing rise in atmospheric CO2, in particular for mire structures with intermediate water table depths.

The Role of Methane Transport From the Active Layer in Sustaining Methane Emissions and Food Chains in Subarctic Ponds. Olid, C.; Zannella, A.; and Lau, D. C. P. Journal of Geophysical Research: Biogeosciences, 126(3): e2020JG005810. 2021. _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005810
Paper   doi   link   bibtex   abstract  

@article{olid_role_2021,
	title = {The {Role} of {Methane} {Transport} {From} the {Active} {Layer} in {Sustaining} {Methane} {Emissions} and {Food} {Chains} in {Subarctic} {Ponds}},
	volume = {126},
	copyright = {© 2021. The Authors.},
	issn = {2169-8961},
	url = {http://agupubs.pericles.prod.literatumonline.com/doi/abs/10.1029/2020JG005810},
	doi = {10.1029/2020jg005810},
	abstract = {Groundwater discharge from the seasonally thawed active layer is increasingly recognized as an important pathway for delivering methane (CH4) into Arctic lakes and streams, but its contribution to CH4 emissions from thaw ponds and its influence on the trophic support and nutritional quality of pond food chains remains unexplored. We quantified the transport of CH4 from the active layer through groundwater discharge into thaw ponds in a subarctic catchment in northern Sweden, using radon (222Rn) as groundwater tracer. We analyzed stable isotopes and fatty acids of pond macroinvertebrates to evaluate the potential effects of groundwater-mediated CH4 inputs on the aquatic food chains. Our results indicate that active layer groundwater discharge flows are nontrivial (range 6\%–46\% of pond volume per day) and the associated CH4 fluxes (median 339 mg C m−2day−1, interquartile range [IQR]: 179–419 mg C m−2 day−1) can sustain the diffusive CH4 emissions from most of the ponds (155 mg C m−2 day−1, IQR: 55–234 mg C m−2 day−1). Consumers in ponds receiving greater CH4 inputs from the active layer had lower stable carbon (C) isotope signatures that indicates a greater trophic reliance on methane oxidizing bacteria (MOB), and they had lower nutritional quality as indicated by their lower tissue concentrations of polyunsaturated fatty acids. Overall, this work links physical (CH4 transport from the active layer), biogeochemical (CH4 emission), and ecological (MOB-consumer interaction) processes to provide direct evidence for the role of active layer groundwater discharge in CH4 cycling of subarctic thaw ponds.},
	language = {en},
	number = {3},
	urldate = {2021-04-01},
	journal = {Journal of Geophysical Research: Biogeosciences},
	author = {Olid, C. and Zannella, A. and Lau, D. C. P.},
	year = {2021},
	note = {\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1029/2020JG005810},
	keywords = {\#nosource, climate change, groundwater, methane, methane-oxidizing bacteria, ponds, trophic chain},
	pages = {e2020JG005810},
}

Groundwater discharge from the seasonally thawed active layer is increasingly recognized as an important pathway for delivering methane (CH4) into Arctic lakes and streams, but its contribution to CH4 emissions from thaw ponds and its influence on the trophic support and nutritional quality of pond food chains remains unexplored. We quantified the transport of CH4 from the active layer through groundwater discharge into thaw ponds in a subarctic catchment in northern Sweden, using radon (222Rn) as groundwater tracer. We analyzed stable isotopes and fatty acids of pond macroinvertebrates to evaluate the potential effects of groundwater-mediated CH4 inputs on the aquatic food chains. Our results indicate that active layer groundwater discharge flows are nontrivial (range 6%–46% of pond volume per day) and the associated CH4 fluxes (median 339 mg C m−2day−1, interquartile range [IQR]: 179–419 mg C m−2 day−1) can sustain the diffusive CH4 emissions from most of the ponds (155 mg C m−2 day−1, IQR: 55–234 mg C m−2 day−1). Consumers in ponds receiving greater CH4 inputs from the active layer had lower stable carbon (C) isotope signatures that indicates a greater trophic reliance on methane oxidizing bacteria (MOB), and they had lower nutritional quality as indicated by their lower tissue concentrations of polyunsaturated fatty acids. Overall, this work links physical (CH4 transport from the active layer), biogeochemical (CH4 emission), and ecological (MOB-consumer interaction) processes to provide direct evidence for the role of active layer groundwater discharge in CH4 cycling of subarctic thaw ponds.

  2020 (1)

Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance. Olid, C.; Klaminder, J.; Monteux, S.; Johansson, M.; and Dorrepaal, E. Global Change Biology, 26(10): 5886–5898. 2020. _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15283
Paper   doi   link   bibtex   abstract  

@article{olid_decade_2020,
	title = {Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance},
	volume = {26},
	copyright = {© 2020 The Authors. Global Change Biology published by John Wiley \& Sons Ltd},
	issn = {1365-2486},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15283},
	doi = {10.1111/gcb.15283},
	abstract = {Thicker snowpacks and their insulation effects cause winter-warming and invoke thaw of permafrost ecosystems. Temperature-dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow-free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long-term net C balance (net ecosystem production) in a subarctic peat plateau subjected to 10 years of experimental winter-warming. By combining 210Pb and 14Cdating of peat cores with peat growth models, we investigated thawing effects on year-round primary production and C losses through respiration and leaching from both shallow and deep peat layers. Winter-warming and permafrost thaw had no effect on the net C balance, but strongly affected gross C fluxes. Carbon losses through decomposition from the upper peat were reduced as thawing of permafrost induced surface subsidence and subsequent waterlogging. However, primary production was also reduced likely due to a strong decline in bryophytes cover while losses from the old C pool almost tripled, caused by the deepened active layer. Our findings highlight the need to estimate long-term responses of whole-year production and decomposition processes to thawing, both in shallow and deep soil layers, as they may contrast and lead to unexpected net effects on permafrost C storage.},
	language = {en},
	number = {10},
	urldate = {2024-03-27},
	journal = {Global Change Biology},
	author = {Olid, Carolina and Klaminder, Jonatan and Monteux, Sylvain and Johansson, Margareta and Dorrepaal, Ellen},
	year = {2020},
	note = {\_eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.15283},
	keywords = {\#nosource, age–depth modelling, carbon accumulation, carbon cycle, climate change, decomposition, peat dating, permafrost thawing, production, snow addition, winter-warming},
	pages = {5886--5898},
}

Thicker snowpacks and their insulation effects cause winter-warming and invoke thaw of permafrost ecosystems. Temperature-dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow-free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long-term net C balance (net ecosystem production) in a subarctic peat plateau subjected to 10 years of experimental winter-warming. By combining 210Pb and 14Cdating of peat cores with peat growth models, we investigated thawing effects on year-round primary production and C losses through respiration and leaching from both shallow and deep peat layers. Winter-warming and permafrost thaw had no effect on the net C balance, but strongly affected gross C fluxes. Carbon losses through decomposition from the upper peat were reduced as thawing of permafrost induced surface subsidence and subsequent waterlogging. However, primary production was also reduced likely due to a strong decline in bryophytes cover while losses from the old C pool almost tripled, caused by the deepened active layer. Our findings highlight the need to estimate long-term responses of whole-year production and decomposition processes to thawing, both in shallow and deep soil layers, as they may contrast and lead to unexpected net effects on permafrost C storage.

  2019 (1)

The Effect of Stream Discharge on Hyporheic Exchange. Mojarrad, B. B.; Betterle, A.; Singh, T.; Olid, C.; and Wörman, A. Water, 11(7): 1436. July 2019.
Paper   doi   link   bibtex   abstract  

@article{mojarrad_effect_2019,
	title = {The {Effect} of {Stream} {Discharge} on {Hyporheic} {Exchange}},
	volume = {11},
	issn = {2073-4441},
	url = {https://www.mdpi.com/2073-4441/11/7/1436},
	doi = {10.3390/w11071436},
	abstract = {Streambed morphology, streamflow dynamics, and the heterogeneity of streambed sediments critically controls the interaction between surface water and groundwater. The present study investigated the impact of different flow regimes on hyporheic exchange in a boreal stream in northern Sweden using experimental and numerical approaches. Low-, base-, and high-flow discharges were simulated by regulating the streamflow upstream in the study area, and temperature was used as the natural tracer to monitor the impact of the different flow discharges on hyporheic exchange fluxes in stretches of stream featuring gaining and losing conditions. A numerical model was developed using geomorphological and hydrological properties of the stream and was then used to perform a detailed analysis of the subsurface water flow. Additionally, the impact of heterogeneity in sediment permeability on hyporheic exchange fluxes was investigated. Both the experimental and modelling results show that temporally increasing flow resulted in a larger (deeper) extent of the hyporheic zone as well as longer hyporheic flow residence times. However, the result of the numerical analysis is strongly controlled by heterogeneity in sediment permeability. In particular, for homogeneous sediments, the fragmentation of upwelling length substantially varies with streamflow dynamics due to the contribution of deeper fluxes.},
	language = {en},
	number = {7},
	urldate = {2019-07-30},
	journal = {Water},
	author = {Mojarrad, Brian Babak and Betterle, Andrea and Singh, Tanu and Olid, Carolina and Wörman, Anders},
	month = jul,
	year = {2019},
	keywords = {\#nosource},
	pages = {1436},
}

Streambed morphology, streamflow dynamics, and the heterogeneity of streambed sediments critically controls the interaction between surface water and groundwater. The present study investigated the impact of different flow regimes on hyporheic exchange in a boreal stream in northern Sweden using experimental and numerical approaches. Low-, base-, and high-flow discharges were simulated by regulating the streamflow upstream in the study area, and temperature was used as the natural tracer to monitor the impact of the different flow discharges on hyporheic exchange fluxes in stretches of stream featuring gaining and losing conditions. A numerical model was developed using geomorphological and hydrological properties of the stream and was then used to perform a detailed analysis of the subsurface water flow. Additionally, the impact of heterogeneity in sediment permeability on hyporheic exchange fluxes was investigated. Both the experimental and modelling results show that temporally increasing flow resulted in a larger (deeper) extent of the hyporheic zone as well as longer hyporheic flow residence times. However, the result of the numerical analysis is strongly controlled by heterogeneity in sediment permeability. In particular, for homogeneous sediments, the fragmentation of upwelling length substantially varies with streamflow dynamics due to the contribution of deeper fluxes.

  2018 (1)

Long-term in situ permafrost thaw effects on bacterial communities and potential aerobic respiration. Monteux, S.; Weedon, J. T.; Blume-Werry, G.; Gavazov, K.; Jassey, V. E. J.; Johansson, M.; Keuper, F.; Olid, C.; and Dorrepaal, E. The ISME Journal, 12(9): 2129–2141. September 2018.
Paper   doi   link   bibtex   abstract   1 download  

@article{monteux_long-term_2018,
	title = {Long-term in situ permafrost thaw effects on bacterial communities and potential aerobic respiration},
	volume = {12},
	issn = {1751-7370},
	url = {https://doi.org/10.1038/s41396-018-0176-z},
	doi = {10.1038/s41396-018-0176-z},
	abstract = {The decomposition of large stocks of soil organic carbon in thawing permafrost might depend on more than climate change-induced temperature increases: indirect effects of thawing via altered bacterial community structure (BCS) or rooting patterns are largely unexplored. We used a 10-year in situ permafrost thaw experiment and aerobic incubations to investigate alterations in BCS and potential respiration at different depths, and the extent to which they are related with each other and with root density. Active layer and permafrost BCS strongly differed, and the BCS in formerly frozen soils (below the natural thawfront) converged under induced deep thaw to strongly resemble the active layer BCS, possibly as a result of colonization by overlying microorganisms. Overall, respiration rates decreased with depth and soils showed lower potential respiration when subjected to deeper thaw, which we attributed to gradual labile carbon pool depletion. Despite deeper rooting under induced deep thaw, root density measurements did not improve soil chemistry-based models of potential respiration. However, BCS explained an additional unique portion of variation in respiration, particularly when accounting for differences in organic matter content. Our results suggest that by measuring bacterial community composition, we can improve both our understanding and the modeling of the permafrost carbon feedback.},
	number = {9},
	journal = {The ISME Journal},
	author = {Monteux, Sylvain and Weedon, James T. and Blume-Werry, Gesche and Gavazov, Konstantin and Jassey, Vincent E. J. and Johansson, Margareta and Keuper, Frida and Olid, Carolina and Dorrepaal, Ellen},
	month = sep,
	year = {2018},
	keywords = {\#nosource},
	pages = {2129--2141},
}

The decomposition of large stocks of soil organic carbon in thawing permafrost might depend on more than climate change-induced temperature increases: indirect effects of thawing via altered bacterial community structure (BCS) or rooting patterns are largely unexplored. We used a 10-year in situ permafrost thaw experiment and aerobic incubations to investigate alterations in BCS and potential respiration at different depths, and the extent to which they are related with each other and with root density. Active layer and permafrost BCS strongly differed, and the BCS in formerly frozen soils (below the natural thawfront) converged under induced deep thaw to strongly resemble the active layer BCS, possibly as a result of colonization by overlying microorganisms. Overall, respiration rates decreased with depth and soils showed lower potential respiration when subjected to deeper thaw, which we attributed to gradual labile carbon pool depletion. Despite deeper rooting under induced deep thaw, root density measurements did not improve soil chemistry-based models of potential respiration. However, BCS explained an additional unique portion of variation in respiration, particularly when accounting for differences in organic matter content. Our results suggest that by measuring bacterial community composition, we can improve both our understanding and the modeling of the permafrost carbon feedback.

  2017 (1)

Effects of warming and increased nitrogen and sulfur deposition on boreal mire geochemistry. Olid, C.; Bindler, R.; Nilsson, M. B.; Eriksson, T.; and Klaminder, J. Applied Geochemistry, 78: 149–157. March 2017. 00000
Paper   doi   link   bibtex   abstract  

@article{olid_effects_2017,
	title = {Effects of warming and increased nitrogen and sulfur deposition on boreal mire geochemistry},
	volume = {78},
	issn = {0883-2927},
	url = {http://www.sciencedirect.com/science/article/pii/S088329271630230X},
	doi = {10.1016/j.apgeochem.2016.12.015},
	abstract = {Boreal mire ecosystems are predicted to experience warmer air temperatures as well as changed deposition loads of nitrogen and sulfur during the coming century. In this study, we hypothesized that vegetation changes that accompany these new environmental conditions alter the chemical composition of peat. To test this hypothesis, we quantified changes in peat geochemistry (Al, Ca, Fe, Mg, Na, P, Pb, and Zn) that have occurred in field manipulation plots exposed to 12 years of warming and nitrogen and sulfur additions in a nutrient-poor boreal mire. In contrast to non-nutrients with a mainly atmospheric origin (i.e. Pb), Al-normalized inventories of micronutrients (Zn and Fe) and macronutrients (P and Ca) were significantly (P \< 0.05) higher as a result of warming. For P and Ca, enrichments were also induced by nitrogen additions alone. These results suggest that mires evolving under increasing temperatures and availability of nitrogen are around two times more effective in storing nutrients in the accumulating peat. Our study provides the first empirical evidence that predicted changes in climate and nitrogen deposition scenarios will increase the retention of Ca, Fe, P, and Zn in surface peat of boreal mires in the near future, which may cause a depletion of nutrients released to inland waters dependent on mire inputs.},
	urldate = {2017-04-28},
	journal = {Applied Geochemistry},
	author = {Olid, Carolina and Bindler, Richard and Nilsson, Mats B. and Eriksson, Tobias and Klaminder, Jonatan},
	month = mar,
	year = {2017},
	note = {00000},
	keywords = {\#nosource, Mire, Nitrogen, Peat geochemistry, climate change, nutrients, temperature},
	pages = {149--157},
}

Boreal mire ecosystems are predicted to experience warmer air temperatures as well as changed deposition loads of nitrogen and sulfur during the coming century. In this study, we hypothesized that vegetation changes that accompany these new environmental conditions alter the chemical composition of peat. To test this hypothesis, we quantified changes in peat geochemistry (Al, Ca, Fe, Mg, Na, P, Pb, and Zn) that have occurred in field manipulation plots exposed to 12 years of warming and nitrogen and sulfur additions in a nutrient-poor boreal mire. In contrast to non-nutrients with a mainly atmospheric origin (i.e. Pb), Al-normalized inventories of micronutrients (Zn and Fe) and macronutrients (P and Ca) were significantly (P < 0.05) higher as a result of warming. For P and Ca, enrichments were also induced by nitrogen additions alone. These results suggest that mires evolving under increasing temperatures and availability of nitrogen are around two times more effective in storing nutrients in the accumulating peat. Our study provides the first empirical evidence that predicted changes in climate and nitrogen deposition scenarios will increase the retention of Ca, Fe, P, and Zn in surface peat of boreal mires in the near future, which may cause a depletion of nutrients released to inland waters dependent on mire inputs.

  2016 (1)

Modeling the downward transport of 210Pb in Peatlands: Initial Penetration‐Constant Rate of Supply (IP-CRS) model. Olid, C.; Diego, D.; Garcia-Orellana, J.; Cortizas, A. M.; and Klaminder, J. Science of The Total Environment, 541: 1222–1231. January 2016. 00005
Paper   doi   link   bibtex   abstract  

@article{olid_modeling_2016,
	title = {Modeling the downward transport of {210Pb} in {Peatlands}: {Initial} {Penetration}‐{Constant} {Rate} of {Supply} ({IP}-{CRS}) model},
	volume = {541},
	issn = {0048-9697},
	shorttitle = {Modeling the downward transport of {210Pb} in {Peatlands}},
	url = {http://www.sciencedirect.com/science/article/pii/S0048969715307920},
	doi = {10.1016/j.scitotenv.2015.09.131},
	abstract = {The vertical distribution of 210Pb is commonly used to date peat deposits accumulated over the last 100–150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of 210Pb within some peat profiles. In this study, we introduce the Initial Penetration–Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived 210Pb (210Pbxs) in peat taking into account both incorporation of 210Pb into the accumulating peat matrix as well as an initial flushing of 210Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous 210Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used 210Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. 241Am and 137Cs). Our results showed that the IP-CRS can provide chronologies from peat records where 210Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene.},
	urldate = {2017-04-28},
	journal = {Science of The Total Environment},
	author = {Olid, Carolina and Diego, David and Garcia-Orellana, Jordi and Cortizas, Antonio Martínez and Klaminder, Jonatan},
	month = jan,
	year = {2016},
	note = {00005},
	keywords = {\#nosource, 137Cs, 210Pb, 241Am, Americium, Caesium, Chronology, Lead},
	pages = {1222--1231},
}

The vertical distribution of 210Pb is commonly used to date peat deposits accumulated over the last 100–150 years. However, several studies have questioned this method because of an apparent post-depositional mobility of 210Pb within some peat profiles. In this study, we introduce the Initial Penetration–Constant Rate of Supply (IP-CRS) model for calculating ages derived from 210Pb profiles that are altered by an initial migration of the radionuclide. This new, two-phased, model describes the distribution of atmospheric-derived 210Pb (210Pbxs) in peat taking into account both incorporation of 210Pb into the accumulating peat matrix as well as an initial flushing of 210Pb through the uppermost peat layers. The validity of the IP-CRS model is tested in four anomalous 210Pb peat records that showed some deviations from the typical exponential decay profile not explained by variations in peat accumulation rates. Unlike the most commonly used 210Pb-dating model (Constant Rate of Supply (CRS)), the IP-CRS model estimates peat accumulation rates consistent with typical growth rates for peatlands from the same areas. Confidence in the IP-CRS chronology is also provided by the good agreement with independent chronological markers (i.e. 241Am and 137Cs). Our results showed that the IP-CRS can provide chronologies from peat records where 210Pb mobility is evident, being a valuable tool for studies reconstructing past environmental changes using peat archives during the Anthropocene.

  2015 (1)

Large difference in carbon emission - burial balances between boreal and arctic lakes. Lundin, E. J.; Klaminder, J.; Bastviken, D.; Olid, C.; Hansson, S. V.; and Karlsson, J. Scientific Reports, 5(5): 14248. 2015. 00005
doi   link   bibtex   abstract  

@article{lundin_large_2015,
	title = {Large difference in carbon emission - burial balances between boreal and arctic lakes},
	volume = {5},
	issn = {2045-2322},
	doi = {10.1038/srep14248},
	abstract = {Lakes play an important role in the global carbon (C) cycle by burying C in sediments and emitting CO2 and CH4 to the atmosphere. The strengths and control of these fundamentally different pathways are therefore of interest when assessing the continental C balance and its response to environmental change. In this study, based on new high-resolution estimates in combination with literature data, we show that annual emission: burial ratios are generally ten times higher in boreal compared to subarctic - arctic lakes. These results suggest major differences in lake C cycling between biomes, as lakes in warmer boreal regions emit more and store relatively less C than lakes in colder arctic regions. Such effects are of major importance for understanding climatic feedbacks on the continental C sink - source function at high latitudes. If predictions of global warming and northward expansion of the boreal biome are correct, it is likely that increasing C emissions from high latitude lakes will partly counteract the presumed increasing terrestrial C sink capacity at high latitudes.},
	language = {English},
	number = {5},
	journal = {Scientific Reports},
	author = {Lundin, E. J. and Klaminder, J. and Bastviken, D. and Olid, C. and Hansson, S. V. and Karlsson, J.},
	year = {2015},
	note = {00005},
	keywords = {\#nosource, Ecosystems, Mineralization, atmosphere, deposition, dioxide, limitation, organic-carbon, sediments, soils, vegetation},
	pages = {14248},
}

Lakes play an important role in the global carbon (C) cycle by burying C in sediments and emitting CO2 and CH4 to the atmosphere. The strengths and control of these fundamentally different pathways are therefore of interest when assessing the continental C balance and its response to environmental change. In this study, based on new high-resolution estimates in combination with literature data, we show that annual emission: burial ratios are generally ten times higher in boreal compared to subarctic - arctic lakes. These results suggest major differences in lake C cycling between biomes, as lakes in warmer boreal regions emit more and store relatively less C than lakes in colder arctic regions. Such effects are of major importance for understanding climatic feedbacks on the continental C sink - source function at high latitudes. If predictions of global warming and northward expansion of the boreal biome are correct, it is likely that increasing C emissions from high latitude lakes will partly counteract the presumed increasing terrestrial C sink capacity at high latitudes.

  2014 (4)

The effects of temperature and nitrogen and sulfur additions on carbon accumulation in a nutrient-poor boreal mire: Decadal effects assessed using 210Pb peat chronologies. Olid, C.; Nilsson, M. B.; Eriksson, T.; and Klaminder, J. Journal of Geophysical Research: Biogeosciences, 119(3): 2013JG002365. March 2014. 00008
Paper   doi   link   bibtex   abstract  

@article{olid_effects_2014,
	title = {The effects of temperature and nitrogen and sulfur additions on carbon accumulation in a nutrient-poor boreal mire: {Decadal} effects assessed using {210Pb} peat chronologies},
	volume = {119},
	issn = {2169-8961},
	shorttitle = {The effects of temperature and nitrogen and sulfur additions on carbon accumulation in a nutrient-poor boreal mire},
	url = {http://onlinelibrary.wiley.com/doi/10.1002/2013JG002365/abstract},
	doi = {10.1002/2013JG002365},
	abstract = {Boreal peatlands are a major long-term reservoir of atmospheric carbon (C) and play an important role in the global C cycle. It is unclear how C accumulation in peatlands responds to changing temperatures and nutrients (specifically, nitrogen and sulfur). In this study, we assessed how the C input rate and C accumulation rate in decadal old peat layers respond to increased air temperatures (+3.6°C) during the growing season and the annual additions of nitrogen (N) and sulfur (S) (30 and 20 kg ha−1 yr−1, respectively) over 12 years of field treatments in a boreal mire. An empirical mass balance model was applied to 210Pb-dated peat cores to evaluate changes in C inputs, C mass loss, and net C accumulation rates in response to the treatments. We found that (i) none of the treatments generated a significant effect on peat mass loss decay rates, (ii) C input rates were positively affected by N additions and negatively affected by S additions, (iii) the C accumulation rate in the uppermost (10 to 12 cm) peat was increased by N additions and decreased by S additions, and (iv) only air temperature significantly affected the main effects induced by N and S additions. Based on our findings, we argue that C accumulation rates in surface peat layers of nutrient-poor boreal mires can increase despite the predicted rise in air temperatures as long as N loads increase and acid atmospheric S remains low.},
	language = {en},
	number = {3},
	urldate = {2017-04-28},
	journal = {Journal of Geophysical Research: Biogeosciences},
	author = {Olid, Carolina and Nilsson, Mats B. and Eriksson, Tobias and Klaminder, Jonatan},
	month = mar,
	year = {2014},
	note = {00008},
	keywords = {\#nosource, 0414 Biogeochemical cycles, processes, and modeling, 0428 Carbon cycling, 0497 Wetlands, 1115 Radioisotope geochronology, 1630 Impacts of global change, 210Pb, Mire, Nitrogen, carbon, climate change, temperature},
	pages = {2013JG002365},
}

Boreal peatlands are a major long-term reservoir of atmospheric carbon (C) and play an important role in the global C cycle. It is unclear how C accumulation in peatlands responds to changing temperatures and nutrients (specifically, nitrogen and sulfur). In this study, we assessed how the C input rate and C accumulation rate in decadal old peat layers respond to increased air temperatures (+3.6°C) during the growing season and the annual additions of nitrogen (N) and sulfur (S) (30 and 20 kg ha−1 yr−1, respectively) over 12 years of field treatments in a boreal mire. An empirical mass balance model was applied to 210Pb-dated peat cores to evaluate changes in C inputs, C mass loss, and net C accumulation rates in response to the treatments. We found that (i) none of the treatments generated a significant effect on peat mass loss decay rates, (ii) C input rates were positively affected by N additions and negatively affected by S additions, (iii) the C accumulation rate in the uppermost (10 to 12 cm) peat was increased by N additions and decreased by S additions, and (iv) only air temperature significantly affected the main effects induced by N and S additions. Based on our findings, we argue that C accumulation rates in surface peat layers of nutrient-poor boreal mires can increase despite the predicted rise in air temperatures as long as N loads increase and acid atmospheric S remains low.

Using Short-lived Radionuclides to Estimate Rates of Soil Motion in Frost Boils. Klaminder, J.; Yoo, K.; Olid, C.; Ramebäck, H.; and Vesterlund, A. Permafrost and Periglacial Processes, 25(3): 184–193. July 2014. 00005
Paper   doi   link   bibtex   abstract  

@article{klaminder_using_2014,
	title = {Using {Short}-lived {Radionuclides} to {Estimate} {Rates} of {Soil} {Motion} in {Frost} {Boils}},
	volume = {25},
	issn = {1099-1530},
	url = {http://onlinelibrary.wiley.com/doi/10.1002/ppp.1811/abstract},
	doi = {10.1002/ppp.1811},
	abstract = {Cryoturbation in high-latitude soils is crucial for the long-term cycling of elements, but the rates of soil motion are poorly constrained. Here, we test whether the rate of frost creep, soil erosion and vertical soil mixing in frost boils can be estimated using short-lived radionuclides (137Cs and 210Pb). We find a small-scale variation in 137Cs and 210Pb inventories in the lower levels of the eroding regions of frost boils in comparison to the expected depositional sites; hence, the distribution of the radionuclides appears to reflect a lateral transport of atmospheric fallout from the centre of the boil (inner domain) towards the surrounding soil (outer domain). 14C dating of the soil indicates that fallout of 137Cs was mobile in the soil and that 210Pb moved with the soil matrix. A soil creep model and a surface soil erosion model are derived and applied to the lateral and vertical distributions of 210Pb in the frost boil. Both models predict the expected trajectories of soil motion and provide rates of creep, erosion and mixing at a mm yr−1 to cm yr−1 scale. The distribution of 210Pb provides new insights about the processes and rates of soil mass movement in frost boils, if sound mass-balance models are applied. Copyright © 2014 John Wiley \& Sons, Ltd.},
	language = {en},
	number = {3},
	urldate = {2017-02-07},
	journal = {Permafrost and Periglacial Processes},
	author = {Klaminder, J. and Yoo, K. and Olid, C. and Ramebäck, H. and Vesterlund, A.},
	month = jul,
	year = {2014},
	note = {00005},
	keywords = {\#nosource, Cryoturbation, carbon-14, cesium-137, frost boils, lead-210},
	pages = {184--193},
}

Cryoturbation in high-latitude soils is crucial for the long-term cycling of elements, but the rates of soil motion are poorly constrained. Here, we test whether the rate of frost creep, soil erosion and vertical soil mixing in frost boils can be estimated using short-lived radionuclides (137Cs and 210Pb). We find a small-scale variation in 137Cs and 210Pb inventories in the lower levels of the eroding regions of frost boils in comparison to the expected depositional sites; hence, the distribution of the radionuclides appears to reflect a lateral transport of atmospheric fallout from the centre of the boil (inner domain) towards the surrounding soil (outer domain). 14C dating of the soil indicates that fallout of 137Cs was mobile in the soil and that 210Pb moved with the soil matrix. A soil creep model and a surface soil erosion model are derived and applied to the lateral and vertical distributions of 210Pb in the frost boil. Both models predict the expected trajectories of soil motion and provide rates of creep, erosion and mixing at a mm yr−1 to cm yr−1 scale. The distribution of 210Pb provides new insights about the processes and rates of soil mass movement in frost boils, if sound mass-balance models are applied. Copyright © 2014 John Wiley & Sons, Ltd.

Incorporation of radiometric tracers in peat and implications for estimating accumulation rates. Hansson, S. V.; Kaste, J. M.; Olid, C.; and Bindler, R. Science of The Total Environment, 493: 170–177. September 2014. 00007
Paper   doi   link   bibtex   abstract  

@article{hansson_incorporation_2014,
	title = {Incorporation of radiometric tracers in peat and implications for estimating accumulation rates},
	volume = {493},
	issn = {0048-9697},
	url = {http://www.sciencedirect.com/science/article/pii/S0048969714007682},
	doi = {10.1016/j.scitotenv.2014.05.088},
	abstract = {Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides 210Pb, 137Cs, 241Am, and 7Be, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of 7Be down to 18–20 cm for some cores, and the broad vertical distribution of 241Am without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age–depth model leads to unrealistic peat mass accumulation rates (400–600 g m− 2 yr− 1), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of 210Pb through the uppermost peat layers, recent peat accumulation rates (200–300 g m− 2 yr− 1) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using 7Be, and if this information is incorporated into age–depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years.},
	urldate = {2017-04-28},
	journal = {Science of The Total Environment},
	author = {Hansson, Sophia V. and Kaste, James M. and Olid, Carolina and Bindler, Richard},
	month = sep,
	year = {2014},
	note = {00007},
	keywords = {\#nosource, Beryllium, Downwash, Lead, Peat accumulation, mercury},
	pages = {170--177},
}

Accurate dating of peat accumulation is essential for quantitatively reconstructing past changes in atmospheric metal deposition and carbon burial. By analyzing fallout radionuclides 210Pb, 137Cs, 241Am, and 7Be, and total Pb and Hg in 5 cores from two Swedish peatlands we addressed the consequence of estimating accumulation rates due to downwashing of atmospherically supplied elements within peat. The detection of 7Be down to 18–20 cm for some cores, and the broad vertical distribution of 241Am without a well-defined peak, suggest some downward transport by percolating rainwater and smearing of atmospherically deposited elements in the uppermost peat layers. Application of the CRS age–depth model leads to unrealistic peat mass accumulation rates (400–600 g m− 2 yr− 1), and inaccurate estimates of past Pb and Hg deposition rates and trends, based on comparisons to deposition monitoring data (forest moss biomonitoring and wet deposition). After applying a newly proposed IP-CRS model that assumes a potential downward transport of 210Pb through the uppermost peat layers, recent peat accumulation rates (200–300 g m− 2 yr− 1) comparable to published values were obtained. Furthermore, the rates and temporal trends in Pb and Hg accumulation correspond more closely to monitoring data, although some off-set is still evident. We suggest that downwashing can be successfully traced using 7Be, and if this information is incorporated into age–depth models, better calibration of peat records with monitoring data and better quantitative estimates of peat accumulation and past deposition are possible, although more work is needed to characterize how downwashing may vary between seasons or years.

Monte Carlo uncertainty calculation of 210Pb chronologies and accumulation rates of sediments and peat bogs. Sanchez-Cabeza, J.; Ruiz-Fernández, A. C.; Ontiveros-Cuadras, J. F.; Pérez Bernal, L. H.; and Olid, C. Quaternary Geochronology, 23: 80–93. October 2014. 00018
Paper   doi   link   bibtex   abstract  

@article{sanchez-cabeza_monte_2014,
	title = {Monte {Carlo} uncertainty calculation of {210Pb} chronologies and accumulation rates of sediments and peat bogs},
	volume = {23},
	issn = {1871-1014},
	url = {http://www.sciencedirect.com/science/article/pii/S1871101414000569},
	doi = {10.1016/j.quageo.2014.06.002},
	abstract = {210Pb dating is a key technique to study sedimentary records of environmental change in the Anthropocene over a time scale of 100–150 years. Uncertainty estimation of 210Pb ages and accumulation rates, when provided by the authors, are usually based on quadratic propagation of uncertainties. In this work, we describe the use of Monte Carlo simulation to estimate 210Pb dating uncertainties in sediment and peat cores. The methodology allows, by using nowadays common computers, the assessment of 210Pb dating uncertainties in a simple manner, using readily-accessible computers and widely-used proprietary spreadsheet software, and avoiding the derivation of rather complex formulae. Results were calculated and compared with quadratic propagation uncertainties in a marine, lacustrine and peat bog core. The analysis of the uncertainty budgets indicated that, overall, the total and unsupported (or base) 210Pb concentrations are the largest contributors to uncertainty, as well as the layer depths when sediment accumulation rates were calculated. Beyond 210Pb dating, the Monte Carlo scheme described here could be used in any field of the analytical sciences, including other radiochronological applications.},
	urldate = {2017-04-28},
	journal = {Quaternary Geochronology},
	author = {Sanchez-Cabeza, Joan-Albert and Ruiz-Fernández, Ana Carolina and Ontiveros-Cuadras, Jorge Feliciano and Pérez Bernal, Libia Hascibe and Olid, Carolina},
	month = oct,
	year = {2014},
	note = {00018},
	keywords = {\#nosource, 210Pb dating, Monte Carlo statistics, Peat bog core, Sediment core, Uncertainty},
	pages = {80--93},
}

210Pb dating is a key technique to study sedimentary records of environmental change in the Anthropocene over a time scale of 100–150 years. Uncertainty estimation of 210Pb ages and accumulation rates, when provided by the authors, are usually based on quadratic propagation of uncertainties. In this work, we describe the use of Monte Carlo simulation to estimate 210Pb dating uncertainties in sediment and peat cores. The methodology allows, by using nowadays common computers, the assessment of 210Pb dating uncertainties in a simple manner, using readily-accessible computers and widely-used proprietary spreadsheet software, and avoiding the derivation of rather complex formulae. Results were calculated and compared with quadratic propagation uncertainties in a marine, lacustrine and peat bog core. The analysis of the uncertainty budgets indicated that, overall, the total and unsupported (or base) 210Pb concentrations are the largest contributors to uncertainty, as well as the layer depths when sediment accumulation rates were calculated. Beyond 210Pb dating, the Monte Carlo scheme described here could be used in any field of the analytical sciences, including other radiochronological applications.

  2013 (1)

Buried soil organic inclusions in non-sorted circles fields in northern Sweden: Age and Paleoclimatic context. Becher, M.; Olid, C.; and Klaminder, J. Journal of Geophysical Research: Biogeosciences, 118(1): 104–111. March 2013. 00012
Paper   doi   link   bibtex   abstract  

@article{becher_buried_2013,
	title = {Buried soil organic inclusions in non-sorted circles fields in northern {Sweden}: {Age} and {Paleoclimatic} context},
	volume = {118},
	issn = {2169-8961},
	shorttitle = {Buried soil organic inclusions in non-sorted circles fields in northern {Sweden}},
	url = {http://onlinelibrary.wiley.com/doi/10.1002/jgrg.20016/abstract},
	doi = {10.1002/jgrg.20016},
	abstract = {Although burial of surface organic soil horizons into deeper mineral soil layers helps drive the long-term buildup of carbon in arctic soils, when and why buried horizons formed as result of cryoturbation in northern Sweden remain unclear. In this study, we used 14C and 210Pb dating to assess when organic matter was buried within non-sorted circles fields near Abisko in northern Sweden. In addition, we used aerial photos from 1959 and 2008 to detect eventual trends in cryogenic activities during this period. We found that organic matter from former organic horizons (stratigraphically intact or partly fragmented) corresponds to three major periods: 0–100 A.D., 900–1250 A.D., and 1650–1950 A.D. The latter two periods were indicated by several dated samples, while the extent of the oldest period is more uncertainty (indicated by only one sample). The aerial photos suggest a net overgrowth by shrub vegetation of previously exposed mineral soil surfaces since 1959. This overgrowth trend was seen in most of the studied fields (92 out of 137 analyzed fields), indicating that the cryogenic activity has mainly decreased in studied non-sorted circles fields since the 1950s. This latter interpretation is also supported by the absence of buried organic layers formed during the last decades. We suggest that the organic matter was buried during the transition from longer cold periods to warmer conditions. We believe these climatic shifts could have triggered regional scale burial of soil organic matter and thus affected how these soils sequestered carbon.},
	language = {en},
	number = {1},
	urldate = {2017-02-07},
	journal = {Journal of Geophysical Research: Biogeosciences},
	author = {Becher, Marina and Olid, Carolina and Klaminder, Jonatan},
	month = mar,
	year = {2013},
	note = {00012},
	keywords = {\#nosource, Arctic, Image processing, Pb-210, Permafrost, cryosphere, and high-latitude processes, Soil, carbon cycling, frost creep, non-sorted circles, radiocarbon},
	pages = {104--111},
}

Although burial of surface organic soil horizons into deeper mineral soil layers helps drive the long-term buildup of carbon in arctic soils, when and why buried horizons formed as result of cryoturbation in northern Sweden remain unclear. In this study, we used 14C and 210Pb dating to assess when organic matter was buried within non-sorted circles fields near Abisko in northern Sweden. In addition, we used aerial photos from 1959 and 2008 to detect eventual trends in cryogenic activities during this period. We found that organic matter from former organic horizons (stratigraphically intact or partly fragmented) corresponds to three major periods: 0–100 A.D., 900–1250 A.D., and 1650–1950 A.D. The latter two periods were indicated by several dated samples, while the extent of the oldest period is more uncertainty (indicated by only one sample). The aerial photos suggest a net overgrowth by shrub vegetation of previously exposed mineral soil surfaces since 1959. This overgrowth trend was seen in most of the studied fields (92 out of 137 analyzed fields), indicating that the cryogenic activity has mainly decreased in studied non-sorted circles fields since the 1950s. This latter interpretation is also supported by the absence of buried organic layers formed during the last decades. We suggest that the organic matter was buried during the transition from longer cold periods to warmer conditions. We believe these climatic shifts could have triggered regional scale burial of soil organic matter and thus affected how these soils sequestered carbon.

  2008 (1)

Role of Surface Vegetation in 210Pb-Dating of Peat Cores. Olid, C.; Garcia-Orellana, J.; Martínez-Cortizas, A.; Masqué, P.; Peiteado, E.; and Sanchez-Cabeza, J. Environmental Science & Technology, 42(23): 8858–8864. December 2008. 00034
Paper   doi   link   bibtex   abstract  

@article{olid_role_2008,
	title = {Role of {Surface} {Vegetation} in {210Pb}-{Dating} of {Peat} {Cores}},
	volume = {42},
	issn = {0013-936X},
	url = {http://dx.doi.org/10.1021/es801552v},
	doi = {10.1021/es801552v},
	abstract = {210Pb-dated ombrotrophic peat cores have been widely used to reconstruct the atmospheric fluxes of heavy metals for the past century. Many of these studies rarely include the overlying vegetation compartment (i.e., the aerial part of vegetation and decayed plant remains) in the analysis although it represents the first layer capturing atmospheric deposition. The aim of this study was to evaluate the radionuclide and Pb content of this biologically active layer in bogs and to assess its implications on the total inventories and the 210Pb-derived chronology. We analyzed two short ombrotrophic peat cores from the same bog (Chao de Lamoso, Galicia, Spain) for 210Pb, artificial radionuclides (137Cs and 241Am), and Pb. The total Pb inventory was underestimated by about 12\% when the plant material was not included in the record. The atmospheric origin of 210Pb and the uptake of 137Cs by roots led to significant activities of these radionuclides in the upper layers. Therefore, removing them from the peat record would imply even larger underestimations of the total inventories, ranging from 25\% to 36\% for 137Cs and from 39\% to 49\% for 210Pb. In contrast to the chronologies inferred from the constant rate of supply (CRS) model when only peat layers are considered, the 210Pb chronology agreed well with artificial radionuclide dating when surface vegetation was included. These results suggest that an accurate peat chronology requires an initial evaluation of the relevance of plant inventories and emphasizes the need of considering the biologically active layer when atmospheric fluxes of heavy metals and other pollutants are reconstructed.},
	number = {23},
	urldate = {2017-04-28},
	journal = {Environmental Science \& Technology},
	author = {Olid, Carolina and Garcia-Orellana, Jordi and Martínez-Cortizas, Antonio and Masqué, Pere and Peiteado, Eva and Sanchez-Cabeza, Joan-Albert},
	month = dec,
	year = {2008},
	note = {00034},
	keywords = {\#nosource},
	pages = {8858--8864},
}

210Pb-dated ombrotrophic peat cores have been widely used to reconstruct the atmospheric fluxes of heavy metals for the past century. Many of these studies rarely include the overlying vegetation compartment (i.e., the aerial part of vegetation and decayed plant remains) in the analysis although it represents the first layer capturing atmospheric deposition. The aim of this study was to evaluate the radionuclide and Pb content of this biologically active layer in bogs and to assess its implications on the total inventories and the 210Pb-derived chronology. We analyzed two short ombrotrophic peat cores from the same bog (Chao de Lamoso, Galicia, Spain) for 210Pb, artificial radionuclides (137Cs and 241Am), and Pb. The total Pb inventory was underestimated by about 12% when the plant material was not included in the record. The atmospheric origin of 210Pb and the uptake of 137Cs by roots led to significant activities of these radionuclides in the upper layers. Therefore, removing them from the peat record would imply even larger underestimations of the total inventories, ranging from 25% to 36% for 137Cs and from 39% to 49% for 210Pb. In contrast to the chronologies inferred from the constant rate of supply (CRS) model when only peat layers are considered, the 210Pb chronology agreed well with artificial radionuclide dating when surface vegetation was included. These results suggest that an accurate peat chronology requires an initial evaluation of the relevance of plant inventories and emphasizes the need of considering the biologically active layer when atmospheric fluxes of heavy metals and other pollutants are reconstructed.