Carbon and nitrogen loss rates during aging of lake sediment: Changes over 27 years studied in varved lake sediment

Gälman, Veronika; Rydberg, Johan; de-Luna, Sara Sjöstedt; Bindler, Richard; Renberg, Ingemar

doi:10.4319/lo.2008.53.3.1076

Cited by 191 publications

(155 citation statements)

References 28 publications

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“…Third, small differences between samples can also be introduced during subsampling, handling, and analyses. Nevertheless, previous studies have shown very good reproducibility for total C and N concentrations between cores (Gä lman et al 2006). This is in agreement with recorded trends in Fig.…”

Section: Discussionsupporting

confidence: 81%

Decadal diagenetic effects on δ¹³C and δ¹⁵N studied in varved lake sediment

Gälman

Rydberg

Bigler

2009

Limnology & Oceanography

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To assess the long-term (27 yr) effects of sediment aging on stable carbon and nitrogen isotope values (d 13 C and d 15 N), we used a collection of eight freeze cores of annually laminated (varved) lake sediment collected from 1979 to 2007 in Nylandssjö n (northern Sweden). Previous research has shown that 20-23% of carbon and 35% of nitrogen is lost in 27 yr. Material from specific years was compared in the cores, e.g., d 13 C and d 15 N of the surface varve of the 1979 core was followed in cores retrieved in 1980, 1989, 1993, 2002, 2004, and 2006. d 13 C increased by 0.4-1.5% during the first 5 yr. After this initial increase, only minor fluctuations were recorded. There is a good correlation between the magnitude in d 13 C changes and the initial carbon and nitrogen concentrations, indicating that the initial sediment composition is important for the 13 C fractionation. d 15 N gradually decreased by 0.3-0.7% over the entire 27-yr period. The lack of correlation with the initial sediment composition and the gradual decrease in d 15 N indicates a microbial control on d 15 N change. The diagenetic changes in the stable isotope values that occur in Nylandssjö n are small, but of the same magnitude as the down-core variation in the varves deposited . Diagenetic effects should be considered when d 13 C and d 15 N are used to study organic matter sources or paleoproductivity, especially when dealing with recent trends or small changes. Based on our findings, diagenetic effects for d 13 C are observed during the first 5-10 yr, whereas no delimitation can be recommended for d 15 N.

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Section: Discussionsupporting

confidence: 81%

Decadal diagenetic effects on δ¹³C and δ¹⁵N studied in varved lake sediment

Gälman

Rydberg

Bigler

2009

Limnology & Oceanography

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“…However, these experiments also indicate that diagenesis was effectively complete after only 25 days. Moreover, an analysis of varved sediments over time has revealed that as much as 20 % of organic C and as much as 30 % of organic N can be lost in situ from lake sediments, but that most of this loss occurs in the first 5 yr following deposition (Gälman et al, 2008). Therefore incomplete diagenesis cannot fully explain the increases in organic C and N that are observed over 100 to 200 yr in these alpine lakes.…”

Section: Implications For Biogeochemistrymentioning

confidence: 92%

Biogeochemical response of alpine lakes to a recent increase in dust deposition in the Southwestern, US

et al. 2011

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Abstract. The deposition of dust has recently increased significantly over some regions of the western US. Here we explore how changes in dust deposition have affected the biogeochemistry of two alpine watersheds in Colorado, US. We first reconstruct recent changes in the mass accumulation rate of sediments and then we use isotopic measurements in conjunction with a Bayesian mixing model to infer that approximately 95 % of the inorganic fraction of lake sediments is derived from dust. Elemental analyses of modern dust indicate that dust is enriched in Ca, Cr, Cu, Mg, Ni, and in one watershed, Fe and P relative to bedrock. The increase in dust deposition combined with its enrichment in certain elements has altered the biogeochemisty of these systems. Both lakes showed an increase in primary productivity as evidenced by a decrease in carbon isotopic discrimination; however, the cause of increased primary productivity varies due to differences in watershed characteristic. The lake in the larger watershed experienced greater atmospheric N loading and less P loading from the bedrock leading to a greater N:P flux ratio. In contrast, the lake in the smaller watershed experienced less atmospheric N loading and greater P loading from the bedrock, leading to a reduced N:P flux ratio. As a result, primary productivity was more constrained by N availability in the smaller watershed. N-limited primary productivity in the smaller watershed was partly ameliorated by an increase in nitrogen fixation as indicated by reduced nitrogen isotopic values in more contemporary sediments. This study illustrates that alpine watersheds are excellent integrators of changes in atmospheric deposition, but that the biogeochemical response of these watersheds may be mediated by their physical (i.e. watershed area) and chemical (i.e. underlying geology) properties.

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“…Accordingly, marine and terrestrial OM is characterized by molar C/N ratios of 20 4-10 and > 20, respectively. However, C/N of OM produced in the euphotic zone is potentially elevated during sinking (Müller, 1977;Meyers, 2003) and diagenesis (Gälman et al, 2008) due to preferential degradation of N over C. Conversely, adsorption of ammonia (produced upon OM decomposition) on to clay mineral surfaces has the potential to decrease sediment C/N during diagenesis especially in sediments with less than 0.3 % of Corg (Müller, 1977). Despite these potential constraints, C/N ratio often accurately records past variations in the source of OM to the seafloor (Meyers, 1994;1997), as suggested for the coastal 25…”

Section: Carbon To Nitrogen Ratiomentioning

confidence: 99%

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

Jokinen¹,

Virtasalo²,

Jilbert³

et al. 2018

Preprint

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Abstract. The anthropogenically forced expansion of coastal hypoxia is a major environmental problem affecting coastal ecosystems and biogeochemical cycles throughout the world. The Baltic Sea is a semi-enclosed shelf sea whose central deep basins have been highly prone to deoxygenation during its Holocene history, as shown previously by numerous paleoenvironmental studies. However, long-term data on past fluctuations in the intensity of hypoxia in the coastal zone of the Baltic Sea are largely lacking, despite the significant role of these areas in retaining nutrients derived from the catchment.Here 5 we present a 1500-year multiproxy record of near-bottom water redox changes from the coastal zone of the northern Baltic Sea, encompassing the climatic phases of the Medieval Climate Anomaly (MCA), the Little Ice Age (LIA), and the Modern Warm Period (MoWP). Our reconstruction shows that although multicentennial climate variability has modulated depositional conditions and delivery of organic matter (OM) to the basin the modern aggravation of coastal hypoxia is unprecedented, and besides gradual changes in the basin configuration, it must have been forced by excess human-induced nutrient loading. The 10 progressive deoxygenation since the beginning of 1900s was originally triggered by the combined effects of gradual shoaling of the basin and warming climate, which amplified sediment focusing and increased the vulnerability to hypoxia. Importantly, the anthropogenic eutrophication of coastal waters in our study area began decades earlier than previously thought, leading to a marked aggravation of hypoxia in the 1950s through fueling primary productivity, while we find no evidence of anthropogenic forcing during the MCA. These results have implications for the assessment of reference conditions for coastal 15 water quality. Furthermore, this study highlights the need for combined use of sedimentological, ichnological, and geochemical proxies in order to robustly reconstruct subtle redox shifts especially in dynamic, non-euxinic coastal settings with strong seasonal contrasts in the bottom water quality. 25Biogeosciences Discuss., https://doi

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Carbon and nitrogen loss rates during aging of lake sediment: Changes over 27 years studied in varved lake sediment

Cited by 191 publications

References 28 publications

Decadal diagenetic effects on δ¹³C and δ¹⁵N studied in varved lake sediment

Decadal diagenetic effects on δ¹³C and δ¹⁵N studied in varved lake sediment

Biogeochemical response of alpine lakes to a recent increase in dust deposition in the Southwestern, US

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century

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Carbon and nitrogen loss rates during aging of lake sediment: Changes over 27 years studied in varved lake sediment

Cited by 191 publications

References 28 publications

Decadal diagenetic effects on δ13C and δ15N studied in varved lake sediment

Decadal diagenetic effects on δ13C and δ15N studied in varved lake sediment

Biogeochemical response of alpine lakes to a recent increase in dust deposition in the Southwestern, US

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20&lt;sup&gt;th&lt;/sup&gt; century

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Decadal diagenetic effects on δ¹³C and δ¹⁵N studied in varved lake sediment

Decadal diagenetic effects on δ¹³C and δ¹⁵N studied in varved lake sediment

A 1500-year multiproxy record of coastal hypoxia from the northern Baltic Sea indicates unprecedented deoxygenation over the 20<sup>th</sup> century