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Emiliya P. Kirilova Maarten van Hardenbroek Oliver Heiri Holger Cremer André F. Lotter 《Journal of Paleolimnology》2010,43(4):829-842
We present a palaeolimnological study encompassing five centuries of trophic-state change of the dike-breach lake De Waay
located on the Rhine-Meuse delta (the Netherlands). Diatom-inferred total phosphorus (TP) concentrations indicate hypertrophic
epilimnetic conditions (>300 μg l−1 TP) since the formation of the lake in the fifteenth century until the end of the eighteenth century. Cladocera data support
the reconstructed trophic state and indicate turbid conditions in lake De Waay during this period. High inferred TP concentrations
as well as the amount of Ti in the sediment reflect numerous flooding events. From the nineteenth century onwards reconstructed
TP concentrations decreased to 40–150 μg l−1 due to improvements in sewage and dike systems that considerably diminished direct river flooding and seepage-derived nutrients.
As a consequence, the increased stability of littoral habitats led to an increased diversity of the Cladocera assemblages.
The most significant decrease in TP concentrations to ~40 μg l−1 occurred between about 1900 and 1930. This mesotrophic phase was a consequence of the isolation of the lake from catchment
drainage and the introduction of a highly elaborate flood control during this period. However, since the mid twentieth century
a eutrophication trend is preserved in the record, likely related to increased agricultural activity in the vicinity of the
lake. Our results emphasize that land-use and trophic-state history must be taken into account when evaluating the ecological
status of lakes for water management and protection actions, especially for lakes in landscapes that are strongly modified
by human action. 相似文献
2.
Climate-driven shifts in diatom assemblages recorded in annually laminated sediments of Sacrower See (NE Germany) 总被引:1,自引:1,他引:0
E. P. Kirilova O. Heiri P. Bluszcz B. Zolitschka A. F. Lotter 《Aquatic Sciences - Research Across Boundaries》2011,73(2):201-210
Sacrower See is a eutrophic lake with annually laminated sediments extending back to A.D. 1868. Analysis of annual layers
revealed multi-decadal periods of distinct diatom assemblages at A.D. 1868–1875, 1876–1940, 1941–1978, and 1979–2000. Detrended
correspondence analysis performed on individual seasonal sediment layers showed decadal-scale patterns of turnover in the
diatom flora. The spring–summer layers showed higher sample scores until the early 1960s, after which the differences with
the autumn–winter layers became smaller. Rates-of-change analysis revealed that the seasonal variability in diatom assemblages
was higher than the annual changes. Summer diatom rates of change over the period A.D. 1894–1960 was on average higher than
for winter, whereas between the 1960s and 1970s the winter rates of change became higher than the summer ones. Redundancy
Analyses showed that seasonal temperatures and wind strength were significant explanatory variables for diatom assemblages
in both annual and seasonal layers. These results suggest that meteorological changes indirectly affected diatom assemblages
via the mixing regime of the lake. A comparison of the diatom rates of change with the amplitude of inter-annual climate change
shows a statistically significant correlation for the spring-summer layers in the period of A.D. 1963–2000, showing that the
sensitivity of diatom assemblages to meteorological changes has varied over the past century, with a stronger effect on diatoms
registered during the past 40 years. 相似文献
3.
Andreas Koutsodendris André F. Lotter Emiliya Kirilova Florence T. M. Verhagen Achim Brauer Jörg Pross 《Boreas: An International Journal of Quaternary Research》2013,42(3):714-728
To provide insights into the long‐term evolution of aquatic ecosystems without human interference, we here evaluate a decadal‐ to centennial‐scale‐resolution diatom record spanning about 12 ka of the Holsteinian interglacial (Marine Isotope Stage 11c). Using a partially varved sediment core from the Dethlingen palaeolake (northern Germany), which has previously been studied for palynological and microfacies signals, we document the co‐evolution of the aquatic and surrounding terrestrial environment. The diatom record is dominated by the genera Stephanodiscus, Aulacoseira, Ulnaria and Fragilaria. Based on the diatom assemblages and physical sediment properties, the evolution of the Dethlingen palaeolake can be subdivided into three major phases. During the oldest phase (lasting ~1900 varve years), the lake was ~10–15 m deep and characterized by anoxic bottom‐water conditions and a high nutrient content. The following ~5600 years exhibited water depths >20 m, maximum diatom and Pediastrum productivity, and a peak in allochtonous nutrient input. During this phase, water‐column mixing became more vigorous, resulting in a breakdown of anoxia. The youngest lake phase (~4000–5000 years) was characterized by decreasing water depth, turbulent water conditions and decreased nutrient loading. Based on our palaeolimnological data, we conclude that the evolution of the Dethlingen palaeolake during the Holsteinian interglacial responded closely to (i) changes within the catchment area (as documented by vegetation and sedimentation) related to the transition from closed forests growing on nutrient‐rich soils (mesocratic forest phase) to open forests developing on poor soils (oligocratic forest phase), and (ii) short‐term climate variability as reflected in centennial‐scale climate perturbations. 相似文献
4.
Philipp Bluszcz Emiliya Kirilova André F. Lotter Christian Ohlendorf Bernd Zolitschka 《Aquatic Geochemistry》2008,14(1):73-98
A 2-year (October 2003–October 2005) high-resolution sediment trap study was conducted in Sacrower See, a dimictic hardwater
lake in northeastern Germany. Geochemical and diatom data from sediment trap samples were compared with a broad range of limnological
and meteorological parameters to quantify the impact of single parameters on biochemical calcite precipitation and organic
matter production. Our goals were to disentangle how carbonaceous varves and their sublaminae form during the annual cycle
to better understand the palaeorecords and to detect influences of dissolution, resuspension as well as of global radiation
and stratification on lake internal particle formation. Total particle fluxes in both investigated years were highest during
spring and summer. Sedimentation was dominated by autochthonous organic matter and biochemically precipitated calcite. Main
calcite precipitation occurred between April and July and was preceded and followed by smaller flux peaks caused by resuspension
during winter and blooms of the calcified green algae Phacotus lenticularis during summer. In some of the trap intervals during summer up to 100% of the precipitated calcite was dissolved in the hypolimnion.
High primary production due to stable insolation conditions in epilimnic waters began with stratification of the water column.
Start and development of stratification is closely related to air and water surface temperatures. It is assumed that global
radiation influences the onset and stability of water column stratification and thereby determining the intensity of primary
production and consequently of timing and amount of calcite precipitation which is triggered by phytoplanktonic CO2 consumption. Sediment fluxes of organic matter and calcite are also related to the winter NAO-Index. Therefore these fluxes
will be used as a proxy for ongoing reconstruction of Holocene climate conditions. 相似文献
5.
The neutrinos from the Big Bang or the Cosmic Neutrino Background (CNB) carry precious information from the early epoch when our universe was only 1 s old. Although not yet directly detected, CNB may be revealed indirectly through cosmological observations due to neutrino important cosmological influence.We review the cosmological role of neutrinos and the cosmological constraints on neutrino characteristics. Namely, we discuss the impact of neutrinos in the early universe: the cosmic expansion, neutrino decoupling, the role of neutrinos in the primordial production of light elements, leptogenesis, etc. We briefly discuss the role of neutrino at later stages of the universe.Due to the considerable cosmological influence of neutrinos, cosmological bounds on neutrino properties from observational data exist. We review the cosmological constraints on the effective number of neutrino species, neutrino mass and mixing parameters, lepton number of the universe, presence of sterile neutrino, etc. 相似文献
6.
We discuss a mechanism for producing baryon density perturbations during the inflationary stage, and study the evolution of the baryon charge density distribution in the framework of the low-temperature baryogenesis scenario. This mechanism may be important for large-scale structure formation in the Universe and, in particular, may be essential for understanding the existence of a characteristic scale of 130 h −1 Mpc (comoving size) in the distribution of the visible matter.
A detailed analysis shows that both the observed very large scale of the visible matter distribution in the Universe and the observed baryon asymmetry value could naturally appear as a result of the evolution of a complex scalar field condensate, formed at the inflationary stage.
Moreover, according to our model, the visible part of the Universe at present may consist of baryonic and antibaryonic regions, sufficiently separated, so that annihilation radiation is not observed. 相似文献
A detailed analysis shows that both the observed very large scale of the visible matter distribution in the Universe and the observed baryon asymmetry value could naturally appear as a result of the evolution of a complex scalar field condensate, formed at the inflationary stage.
Moreover, according to our model, the visible part of the Universe at present may consist of baryonic and antibaryonic regions, sufficiently separated, so that annihilation radiation is not observed. 相似文献
7.
D. Enters E. Kirilova A. F. Lotter A. Lücke J. Parplies S. Jahns G. Kuhn B. Zolitschka 《Journal of Paleolimnology》2010,43(4):719-737
Lacustrine sediments in north-eastern Germany have rarely been used as archives to address the effects of climate change and
human impact on both lake ecosystem and landscape evolution for this region. Sacrower See, a hardwater lake located in Brandenburg,
provides a unique sediment record covering the past 13,000 years which was used to reconstruct climatic and anthropogenic
forcing on lacustrine sedimentation. Time control is provided by 12 AMS 14C dates of terrestrial plant remains, the Laacher See Tephra, and the onset of varve formation in AD 1870 (80 cal. BP). Geochemical
(including XRF logging of major elements, CNS analyses as well as δ13Corg and δ15N measurements) and pollen analyses allowed detecting detailed environmental changes in the sediment record. During the Younger
Dryas cold phase increased soil erosion and hypolimnetic oxygen depletion enhanced the nutrient supply to the lake water causing
eutrophic conditions. The beginning of the Holocene is characterized by large changes in C/N ratios, total sulphur, δ13C of bulk organic matter as well as in K, Si, and Ti, reflecting the response of the lake’s catchment to climatic warming.
Reforestation reduced the influx of detrital particles and terrestrial organic matter. The first, rather weak evidence of
human impact is documented only in the pollen record at 5,500 cal. BP. However, until 3,200 cal. BP sedimentological and geochemical
parameters indicate relatively stable environmental conditions. During periods of intense human impact at around 3,200, 2,800,
and 900 cal. BP peaks in Ti and K represent phases of increased soil erosion due to forest clearing during the Bronze Age,
Iron Age, and Medieval Times, respectively. In general, greater variation is observed in most variables during these perturbations,
indicating less stable environmental conditions. The steady rise of biogenic silica accumulation rates during the Holocene
reflects an increasing productivity of Sacrower See until diatoms were outcompeted by other algae during the last centuries.
The applied multi-proxy approach fosters the interpretation of the sediment record to reveal a consistent picture of environmental
change including environmental factors controlling lake ontogeny and the effects of human impact. 相似文献
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