A late Holocene record of solar-forced atmospheric blocking variability over Northern Europe inferred from varved lake sediments of Lake Kuninkaisenlampi

Saarni, Saija; Muschitiello, Francesco; Weege, Stefanie; Brauer, Achim; Saarinen, Timo

doi:10.1016/j.quascirev.2016.10.019

Cited by 25 publications

(30 citation statements)

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“…The bulk sediment δ 13 C org signature (from −23.9 to −22.2 ‰) together with the low C / N ratios (from 8.6 to 9.9) indicates that most of the OM deposited in the Haverö basin originates from autochthonous primary productivity rather than from terrestrial sources (e.g., Meyers, 1994Meyers, , 1997, agreeing with the findings from analogous settings in the Swedish archipelago areas (Jönsson et al, 2005b;Savage et al, 2010;Ning et al, 2018). The marked positive correlation of BIT index and C / N ratio as well as their negative correlation with δ 13 C org ( Fig.…”

Section: Organic Matter Input 621 Source Of the Deposited Organic Msupporting

confidence: 86%

“…Indeed, in agreement with the population growth records for Finland (Kuosmanen et al, 2016, and references therein), marked human-induced land-use changes in the catchments of varved lakes in southwestern and south-central Finland became discernible at ∼ 1400 AD (Tiljander et al, 2003;Ojala and Alenius, 2005). This interval coincides with the onset of the LIA, during which both precipitation (Väliranta et al, 2007;Helama et al, 2009;Luoto, 2009;Saarni et al, 2015) and soil erosion rate (Tiljander et al, 2003;Ojala and Alenius, 2005;Saarni et al, 2016) increased in south-central Finland. However, this period is characterized by a shift to suppressed primary productivity at our study site, implying no influence of enhanced external nutrient inputs.…”

Section: Temporal Fluctuations In the Organic Matter Inputsupporting

confidence: 82%

“…This later shift was likely fueled by the concomitant substantial increase in nutrient loading from urban and agricultural sources in the catchment (Fig. 6), being in line with eutrophication trajectories elsewhere in the Baltic Sea linked to amplified anthropogenic nutrient inputs (Struck et al, 2000;Conley et al, 2009a;Savage et al, 2010;Gustafsson et al, 2012;Carstensen et al, 2014a). Finally, we infer that while C org MAR during the MoWP has clearly exceeded the MCA levels (Fig.…”

Section: Temporal Fluctuations In the Organic Matter Inputsupporting

confidence: 71%

“…The progressive increase in the δ 15 N values, beginning already before the turn of the 20th century, attests to recent increased anthropogenic nutrient loading from agriculture and urban sources to the Baltic Sea (Voss and Struck, 1997;Struck et al, 2000;Voss et al, 2000Voss et al, , 2005Savage et al, 2010). This is supported by the contemporaneous exponential population increase in Turku, which combined with the construction of a sewer network for the city likely enhanced sewage loading to the Archipelago Sea (Fig.…”

Section: Temporal Fluctuations In the Organic Matter Inputmentioning

confidence: 92%

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

et al. 2018

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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 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 the depositional conditions and delivery of organic matter (OM) to the basin the modern aggravation of coastal hypoxia is unprecedented and, in addition to gradual changes in the basin configuration, it must have been forced by excess human-induced nutrient loading. Alongside the anthropogenic nutrient input, the progressive deoxygenation since the beginning of the 1900s was fueled 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 eutrophication of coastal waters in our study area began decades earlier than previously thought, leading to a marked aggravation of hypoxia in the 1950s. We find no evidence of similar anthropogenic forcing during the MCA. These results have implications for the assessment of reference conditions for coastal 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.

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Section: Organic Matter Input 621 Source Of the Deposited Organic Msupporting

confidence: 86%

Section: Temporal Fluctuations In the Organic Matter Inputsupporting

confidence: 82%

Section: Temporal Fluctuations In the Organic Matter Inputsupporting

confidence: 71%

Section: Temporal Fluctuations In the Organic Matter Inputmentioning

confidence: 92%

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

et al. 2018

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“…CC BY 4.0 License. of the LIA, during which both precipitation (Väliranta et al, 2007;Helama et al, 2009;Luoto, 2009;Saarni et al, 2015) and soil erosion rate (Tiljander et al, 2003;Ojala and Alenius, 2005;Saarni et al, 2016) increased in south-central Finland.…”

Section: ) 25mentioning

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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Rhyolitic and dacitic component of the Askja 1875 tephra in southern and central Finland: first step towards a Finnish tephrochronology

Kalliokoski

Wastegård

Saarinen

2018

J Quaternary Science

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Tephra from Icelandic volcanic eruptions is frequently dispersed to northern Europe, but so far tephra has not been detected in Finnish sedimentary records. We report the first finding of a cryptotephra layer in southern and central Finland. Sediment samples from five lakes and 10 peatlands, most of them located in the tephra fallout zone of the Hekla 1947 eruption, were investigated for the presence of cryptotephra to assess the potential for tephrochronology in Finland. Tephra shards were extracted from their host matrix and electron probe microanalysis was conducted on single shards for geochemical characterization. Our results confirm the presence of Askja 1875 tephra in Finland, thus extending the known dispersal area of the Askja 1875 tephra eastwards. Most of the shards are rhyolitic, but a minor concentration of tephra with dacitic composition forms a narrow dispersal zone extending from Sweden to southern Finland. This zone possibly represents the main dispersal axis of the tephra in the distal area. Our results suggest that Finnish environmental research could benefit greatly from adding tephrochronology to the array of dating methods commonly used. Additionally, the absence of Hekla 1947 tephra in the previously inferred fall‐out zone is an important result indicating the complexity of tephra deposition and preservation.

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A late Holocene record of solar-forced atmospheric blocking variability over Northern Europe inferred from varved lake sediments of Lake Kuninkaisenlampi

Cited by 25 publications

References 70 publications

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

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

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

Rhyolitic and dacitic component of the Askja 1875 tephra in southern and central Finland: first step towards a Finnish tephrochronology

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A late Holocene record of solar-forced atmospheric blocking variability over Northern Europe inferred from varved lake sediments of Lake Kuninkaisenlampi

Cited by 25 publications

References 70 publications

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

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

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

Rhyolitic and dacitic component of the Askja 1875 tephra in southern and central Finland: first step towards a Finnish tephrochronology

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