Urban contamination sources reflected in inorganic pollution in urban lake deposits, Bergen, Norway

2015 ◽  
Vol 17 (4) ◽  
pp. 854-867 ◽  
Author(s):  
Malin Andersson ◽  
Ola Anfin Eggen
Keyword(s):  
Lake Sediments ◽  
Urban Lake ◽  
Chemical Changes ◽  
Modern City ◽  
Contamination Sources ◽  
Pristine Environment ◽  
Lake Deposits

The 7000 years transition from a pristine environment towards a modern city has brought a number of chemical changes and effects to urban lake sediments in Bergen.

scholarly journals Uranium-series isotopes from Eemian lake deposits, Hollerup, Denmark

1998 ◽  
Vol 44 ◽  
pp. 173-179
Author(s):  
C. Israelson ◽  
S. Bjorck ◽  
N. Noe Nygaard ◽  
C. J. Hawkesworth
Keyword(s):  
Ground Water ◽  
Lake Sediments ◽  
Sedimentary Facies ◽  
Organic Content ◽  
Time Interval ◽  
Decay Products ◽  
Large Spread ◽  
Isotope Study ◽  
Lake Deposits ◽  
High Organic Content

We report the results of a U-series isotope study on Eemian lake sediments from Hollerup, western Denmark. The purpose is to examine the possibility of dating these, and similar, sediments with the 238U-23"h method. Two sedimentary facies were studied; carbonate-present, and virtually carbonate-free but organic-rich sediments. All carbonate-present sediments (5-95%) have (230ThP38U) values higher than unity and relatively radiogenic (23"W232Th) values between 2 and 6.5, indicating postdeposition removal of U, probably by percolation of ground water. Carbonate-free sediments, but with high organic content (40-60%) had (230Th/238U) values lower than 1 and 'model ages' between 89 and 199 ky. The large spread in ages and variation in U content for these sediment samples that were deposited over a much shorter time interval, indicate a complex postdepositional migration pattern of U, probably involving several episodes of leaching and absorption of U from ground water. Our results suggest that lake sediments, such as those found in Hollerup, are vulnerable to mobilization of U and its decay products and care should be taken when interpreting U-series disequilibrium data from such sediments. Future studies will concentrate on sediments that have been more deeply buried andor are less compacted and sealed from percolation of oxidized groundwater.

scholarly journals The rapid increases in microplastics in urban lake sediments

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mingtan Dong ◽  
Zejiao Luo ◽  
Qingfeng Jiang ◽  
Xinli Xing ◽  
Qiaoqiao Zhang ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Urban Lake

scholarly journals Lake Sediments from the Kashmir Himalayas: Inverted 14C Chronology and Its Implications

Radiocarbon ◽  
1992 ◽  
Vol 34 (3) ◽  
pp. 561-565 ◽  
Author(s):  
Sheela Kusumgar ◽  
D. P. Agrawal ◽  
Narendra Bhandari ◽  
R. D. Deshpande ◽  
Alok Raina ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Lake Sediments ◽  
Sedimentation Rate ◽  
Catchment Area ◽  
Inversion Layer ◽  
The Core ◽  
Manasbal Lake ◽  
Mineral Magnetic ◽  
Lake Deposits

We have measured 14C, 210Pb and 137Cs profiles in two representative cores from Manasbal Lake, Kashmir, India. The sedimentation rate derived from 210Pb and 137Cs in the upper part of the core is in the range of 3.4 to 5.5 mm yr−1. In contrast, 14C ages show an inversion at depths >20 cm. These results are attributed to the erosion of the ubiquitous 10–20-m-thick loess mantle, based on the similarity of 14C ages of the inversion layer in the sediments and the paleosols present in the catchment area. Frequency-dependent mineral magnetic susceptibility (χfd), carbon to nitrogen ratios and pigment concentrations in the profile show a significant amount of allochthonous component in the lake deposits and support the conclusion that the 14C dates do not reflect the chronology of the in-situ lake sedimentation but episodic deposition of the surrounding loess. Thus, 14C serves as a useful tracer to understand source components of the sediments.

CARBONATE MINERALOGY OF LAKE SEDIMENTS AND SURROUNDING SOILS 1. BLACKSTRAP LAKE

1983 ◽  
Vol 63 (2) ◽  
pp. 245-257 ◽  
Author(s):  
K. GHEBRE-EGZIABHIER ◽  
R. J. ST. ARNAUD
Keyword(s):  
Lake Sediments ◽  
Lake Water ◽  
Ionic Concentration ◽  
Historical Background ◽  
Sediment Composition ◽  
Sand Fraction ◽  
Reservoir Sediment ◽  
Lake Deposits ◽  
Secondary Magnesium ◽  
Drainage Waters

The carbonate mineralogy of the Blackstrap Lake sediments in central Saskatchewan indicates that the lake deposits are composed of carbonatic minerals similar to those found in surrounding soils and glacial deposits. Textural differences reflect the transport of finer materials (silts and clay) from the adjacent eroding landscapes. In particular the persistence of dolomite in the silt fractions of the lake sediment is a good indication that part of the calcite together with the dolomite are derived from surrounding soils. The sediment sand fraction contains appreciable Mg-bearing calcite and mollusk shells of pure calcite. Changes in the ionic concentrations of the lake water indicate that dissolution-precipitation processes have affected sediment composition. The increased calcium carbonate equivalent percentages and the presence of secondary magnesium-bearing calcites in the lake sediments suggest that this is so, particularly since erosional processes could not account entirely for the differences observed between the sediments and surrounding soils. The presence of gypsum and the nature of the secondary calcites in the Blackstrap Reservoir sediment tie in well with the known historical background of the Reservoir. The increased ionic concentration of the lake water over the last 15 yr or so since the original inception of the Reservoir is attributed to the influx of drainage waters, evaporation and possibly the effects of groundwater entry from below. Key words: Mg-bearing calcite, dolomite, IAP, erosion

The Torridon Group

2002 ◽  
Vol 24 (1) ◽  
pp. 29-46 ◽  
Keyword(s):  
Lake Sediments ◽  
Lower Cambrian ◽  
Red Sandstone ◽  
Maximum Thickness ◽  
Lithostratigraphic Unit ◽  
Gneiss Complex ◽  
Head Formation ◽  
Group Form ◽  
Lake Deposits ◽  
Unconformity Surface

The group unconformably overlies both the Lewisian gneiss complex and the Stoer Group, and is in turn unconformably overlain by the Lower Cambrian (Figs 2 & 22). The unconformity surface at the base is generally rugged, with relief reaching 600 m. The maximum thickness of the Torridon Group is about 7 km onshore and 6 km offshore in the Sea of the Hebrides basin (Stein 1988, fig. 11; 1992, fig. 2B), but albitization of the highest beds indicates that the original thickness was 3-4 km greater. Lake deposits at the bottom of the group occupying palaeovalleys in the gneiss are followed by kilometres of red sandstones, all deposited in a subsiding rift. Alluvial sands interfinger with lake sediments to form cyclothems at the top of the group. As mentioned in the Introduction the Torridon Group is by far the most extensive and voluminous part of the Torridonian (see Plate 1), but nevertheless poses fewer problems of interpretation than the Stoer and Sleat Groups.The formal stratigraphy established by the Geological Survey (Geikie 1894) has been retained even though it is in some respects unsatisfactory. The sediments filling the palaeovalleys at the base of the group form a well-defined lithostratigraphic unit, the Diabaig Formation, characterized by breccias and sandstones derived from the immediately adjacent basement (Fig. 23). The Cailleach Head Formation at the top of the Group is also a valid lithostratigraphic unit, formed of coarsening-upward cyclothems of grey shale and red sandstone. The bulk of the Torridon Group, however, is

Methanogen microfossils and methanogenesis in Permian lake deposits

Geology ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 13-18
Author(s):  
Funing Sun ◽  
Wenxuan Hu ◽  
Xiaolin Wang ◽  
Jian Cao ◽  
Bin Fu ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Metabolic Activity ◽  
Fossil Record ◽  
Methanogenic Archaea ◽  
Ancient Lakes ◽  
Ecological Diversity ◽  
Significant Component ◽  
Biogenic Methane ◽  
Biological Affinity ◽  
Lake Deposits

Abstract Methanogens are methane-producing archaea (some of the most primitive organisms on Earth), which possess great phylogenetic and ecological diversity in modern ecosystems. However, cellular fossil evidence of methanogens remains extremely scarce throughout the geological record. Here, we report a new population of spheroidal microstructures composed of dolomite observed in Permian lake deposits in northwestern China. The microspheres exhibit indicators of biological affinity and are well preserved in authigenic dolomite with cellular fidelity. Based on morphological and geochemical evidence, these microspheres are interpreted as fossilized cells of methanogenic archaea, which can be divided into three size-based taxa. These microfossils are the first fossil record of spheroidal methanogens. The microfossil-bearing dolomite exhibits extremely positive δ13C values (up to +20‰ relative to Vienna Peedee belemnite) that are attributed to microbial methanogenesis. The results suggest that methanogens were a significant component of this Permian lake biosphere. As a consequence of the metabolic activity of the methanogens, a large amount of biogenic methane was produced through methanogenesis in the anoxic lake sediments. This study not only fills a gap in the fossil record of methanogenic archaea, but it also provides new insights into methane emissions from ancient lakes.

Reconstruction of historical atmospheric Pb using Dutch urban lake sediments: A Pb isotope study

2014 ◽  
Vol 484 ◽  
pp. 185-195 ◽  
Author(s):  
N. Walraven ◽  
B.J.H. van Os ◽  
G.Th. Klaver ◽  
J.J. Middelburg ◽  
G.R. Davies
Keyword(s):  
Lake Sediments ◽  
Urban Lake ◽  
Pb Isotope ◽  
Isotope Study

scholarly journals Post-depositional vivianite formation alters sediment phosphorus records

2017 ◽  
Author(s):  
Nikki Dijkstra ◽  
Mathilde Hagens ◽  
Matthias Egger ◽  
Caroline P. Slomp
Keyword(s):  
Lake Sediments ◽  
Marine Sediments ◽  
Reactive Transport ◽  
Transport Model ◽  
Sediment Geochemistry ◽  
Depth Interval ◽  
Sediment Depth ◽  
Marine Deposits ◽  
Phosphate Mineral ◽  
Lake Deposits

Abstract. Phosphorus (P) concentrations in sediments are frequently used to reconstruct past environmental conditions in freshwater and marine systems, with high values thought to be indicative of a high biological productivity. Recent studies suggest that the post-depositional formation of vivianite, an iron(II)-phosphate mineral, might significantly alter trends in P with sediment depth. To assess its importance, we investigate a sediment record from the Bornholm Basin that was retrieved during the IODP Baltic Sea Paleoenvironment Expedition 347 in 2013, consisting of lake sediments overlain by brackish-marine deposits. Combining bulk sediment geochemistry with micro-analysis using scanning electron microscope energy dispersive spectroscopy (SEM-EDS) and synchrotron-based X-ray absorption spectroscopy (XAS), we demonstrate that manganese- and magnesium-rich vivianite is present in the lake deposits just below the transition to the brackish-marine sediments (at 11.5 to 12 m sediment depth). In this depth interval, phosphate that diffuses down from the organic-rich, brackish-marine sediments meets porewaters rich in dissolved iron in the lake sediments, resulting in vivianite precipitation. Results from a reactive transport model suggest that the peak in vivianite originally occurred at the lake-marine transition (9 to 10 m) and moved downwards due to changes in the depth of a sulfidization front. However, its current position relative to the lake-marine transition is stable as the vivianite and active sulfidization fronts have been spatially separated over time. Experiments in which vivianite was subjected to sulfidic conditions demonstrate that incorporation of manganese or magnesium in vivianite does not affect its susceptibility to sulfide-induced dissolution. Our work highlights that post-depositional vivianite formation has the potential to strongly alter sedimentary P records particularly in systems that are subject to environmental perturbation, such as a change in primary productivity, which can be associated with a lake-marine transition.

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