Time averaging and stratigraphic unmixing: reconstructing ecological decline in molluscan production (Holocene, Brijuni, NE Adriatic)

2020 ◽  
Author(s):  
Adam Tomašových ◽  
Martin Zuschin ◽  
Ivo Gallmetzer ◽  
Alexandra Haselmair
Keyword(s):  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Coralline Algae ◽  
Time Averaging ◽  
Sedimentation Rates ◽  
Amino Acid Racemization ◽  
Ecological History ◽  
Shell Bed ◽  
Warm Temperate

<p>The northeastern Adriatic seafloor is formed by warm-temperate bioclastic carbonates with coralline algae, bryozoans and mollusks. These sediments represent a mixture of past and present-day production owing to low sedimentation rates and bioturbation. Although low sedimentation rates do not allow resolution of ecological history at centennial or even millennial scales on the basis of raw stratigraphic data, age unmixing based on radiocarbon-calibrated amino acid racemization shows that one of the major molluscan sediment producers – the infaunal suspension-feeder Timoclea ovata  – markedly peaked in production ~5,000 years during the maximum flooding and earliest highstand phase and significantly diminished in abundance during the late highstand phase at Brijuni, with a large proportion of dead shells now present in surface sediments representing shells that are several centuries old. This species still occurs in living assemblages but our analyses indicate that its former production was by several orders of magnitude higher. In contrast, stratigraphic trends in absolute and proportional abundance of this species in ~1.5 m-thick sediment cores show a gradual or a very mild upcore decline, indicating that raw stratigraphic data do not efficiently detect millennial-scale ecological dynamic. The temporal decline in production of Timoclea ovata is associated with an increase in water depth and an increase in sediment-accumulation rate, and led to a transition from molluscan oyster-scallop shell bed to late highstand bryomol sediments.</p>

Pigment Preservation in Lake Sediments: A Comparison of Sedimentary Environments in Trout Lake, Wisconsin

1991 ◽  
Vol 48 (3) ◽  
pp. 472-486 ◽  
Author(s):  
James P. Hurley ◽  
David E. Armstrong
Keyword(s):  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Sediment Surface ◽  
Water Interface ◽  
Sedimentary Pigments ◽  
Sedimentary Environments ◽  
Trout Lake ◽  
Secondary Carotenoids ◽  
Β Carotene

Fluxes and concentrations of a phorbins and major algal carotenoids were quantified in sediment trap material and sediment cores from two basins of Trout Lake, Wisconsin (TrDH and TrAB). The basins were chosen to contrast the influence of oxygen content at the sediment–water interface (TrDH, oxic and TrAB, reducing), sediment accumulation rate, and focusing. Pigment diagenesis occurred in both basins, but transformations and destruction were more extensive in TrDH. Although untransformed chlorophyll a was the major phorbin deposited at the sediment surface of both basins (51–64 mol%), pigment destruction, coupled with transition to pheophytin, accounted for substantial losses, especially in oxic TrDH sediments. Fucoxanthin, peridinin, and diadinoxanthin, despite representing > 70% of the deposited carotenoid flux, were substantially degraded or transformed in both basins. However, preservation was relatively high for secondary carotenoids, such as diatoxanthin and β-carotene, and for a major cryptomonad pigment, alloxanthin. Residual profiles in sediments show that pigment sedimentation from the epilimnion and accumulation in the permanent sediments are not directly related and that diagenesis must be considered in interpreting sedimentary pigments.

Sedimentological and limnological evolution of recreational lakes in a former asbestos mining region (Québec, Canada): insights from paleolimnology

2020 ◽  
Author(s):  
Reinhard Pienitz ◽  
Olivier Jacques
Keyword(s):  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Ecological Condition ◽  
Nutrient Concentrations ◽  
Mineral Matter ◽  
Mining Activities ◽  
Fine Grained ◽  
Efficient Management ◽  
A Chain

<p>The Bécancour River basin in southern Québec (Canada) has been impacted by more than a hundred years of asbestos mining activities in the Thetford Mines region. Several recreational water bodies located downstream from the city are suffering from high sediment and contaminant loads and eutrophication. In order to prepare an efficient management of the fluvial lakes, we completed paleolimnological investigations to evaluate the extent of their deterioration and identify catchment disturbances that influenced their present-day condition. Here we present the results of a multi-proxy study of sediment cores collected from a chain of 5 lakes. The sedimentary records from these lakes indicate severe perturbations associated with the complete draining of Lac Noir, a former lake near Thetford Mines excavated and drained for mining purposes between 1955-1959. Radiometric <sup>210</sup>Pb dating revealed extreme increases in the sediment accumulation rate following this event. Analyses of loss-on-ignition, carbon (C) and nitrogen (N) isotopes, grain-size, and X-ray microfluorescence indicated that the post-1960 sediments were enriched in fine-grained mineral matter and had higher metal and nutrient concentrations as compared to older sediments at the bottom of the cores. Changes in the δ<sup>13</sup>C and C/N ratios and the predominance of diatom taxa (class Bacillariophyceae) typical of nutrient-rich waters (e.g., Cyclostephanos invisitatus, Cyclotella meneghiniana) also showed that the 1955-1959 event led to a rapid eutrophication of some lakes. Results from our study illustrate that the asbestos mining activities had dramatic impacts on lake biota and contaminant levels, and suggest that major restoration efforts will be needed to improve their ecological condition.</p>

scholarly journals SEDIMENT ACCUMULATION PROFILE IN MANGROVE RESTORATION AREA OF LEMBAR BAY-LOMBOK ISLAND

2017 ◽  
Vol 9 (1) ◽  
pp. 301-313
Author(s):  
Mohammad Sumiran Paputungan ◽  
Alan Frendy Koropitan ◽  
Tri Prartono ◽  
Ali Arman Lubis
Keyword(s):  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Coastal Region ◽  
Sediment Accumulation Rate ◽  
Ecosystem Functions ◽  
Sampling Location ◽  
Mangrove Restoration ◽  
Mangrove Area ◽  
Lombok Island

Mangrove restoration is really needed for restoring its ecosystem functions, so that it could be able to support fisheries activity and to protect coastal by extreme weather. In addition, mangrove is able to accumulate sediment that important in protecting the coastal area from sea level rise. Therefore,  the aim of this study is to investigate sediment accumulation rate in mangrove area during post restoration. Sampling location were divided into three different stations based on estimated restoration ages, such as ≥ 15  years old (Station 1), 4 - 10 years old (Station 2) and 2 - 8 years old (Station 3). Sediment cores were carried out by inserting 7.6 cm diameter and 100 cm length of polyvinyl chloride pipes. Sedimentation rate is measured by using Pb-210 radionuclide analysis. The results show that the sediment accumulation rate in the last 20th years from all station ranges from 0.17 to 0.42 g/cm2/year. The highest accumulation rate is found at oldest year old station while the lowest accumulation rate is found at younger year old station of mangrove restoration area. Restoration process is clearly able to recover the mangrove’s role in trapping sediment in coastal region. Keywords: sediment accumulation, mangrove restoration, Lembar Bay-                   Lombok Island 

scholarly journals Evaluating the historical sedimentation patterns in two different Mediterranean deep environments (Sardinia and Sicily Channels)

2019 ◽  
Vol 20 (3) ◽  
pp. 542 ◽  
Author(s):  
NOUR EL HOUDA HASSEN ◽  
NAFAÂ REGUIGUI ◽  
MOHAMED AMINE HELALI ◽  
NEZHA MEJJAD ◽  
ABDELMOURHIT LAISSAOUI ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Water Depth ◽  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Inverse Correlation ◽  
Accumulation Rates ◽  
Deep Sediment ◽  
210Pb And 137Cs ◽  
Excess 210Pb

The sediment accumulation rate in the Sardinia and Sicily channels in the central part of the Mediterranean Sea was studied by using short-lived radionuclides (210Pb and 137Cs) in two deep sediment cores. Different sedimentation regimes were identified indicating substantial differences in accumulation rates and historical patterns. The 210Pb-derived mean accumulation rate found in the Strait of Sardinia was 0.05 g.cm-2.y-1, lower than that in Sicily Channel (0.1 g.cm-2.y-1) suggesting an inverse correlation with water depth. Excess 210Pb inventories were 24 ± 1 and 6.0 ± 0.4 kBq.m-2, while the fluxes to the sediment were 745 ± 31 and 188 ± 11 Bq.m-2.y-1 in Sicily and Sardinia channels, respectively. 137Cs failed to use for the validation of the established chronologies, while its inventories found 450 Bq.m-2 and 355 Bq.m-2 in the Sicily and Sardinia channel, respectively.

Holocene sedimentation in glacial Tasikutaaq Lake, Baffin Island

1988 ◽  
Vol 25 (6) ◽  
pp. 810-823 ◽  
Author(s):  
Donald S. Lemmen ◽  
Robert Gilbert ◽  
John P. Smol ◽  
Roland I. Hall
Keyword(s):  
Drainage Basin ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Late Glacial ◽  
Sediment Concentration ◽  
Diatom Assemblage ◽  
Laminated Sediments ◽  
Sedimentation Rates ◽  
Baffin Island ◽  
Sediment Input

Tasikutaaq Lake, on Cumberland Peninsula, Baffin Island, receives inflow and fine sediment from a 448 km2 drainage basin, 21% of which is glacier covered. During the summer of 1983 the lake remained essentially isothermal between about 4 and 6 °C. The suspended sediment concentration of inflow never exceeded 100 mg L−1 with overflow and homopycnal flow dominant.Surface sediments are clearly laminated, although varves are not apparent. The sediments are very fine, with less than 3% sand in all but the most proximal sites. Average sedimentation rates between 1976 and 1983 ranged from about 4 mm a−1 to 0.25 mm a−1 down lake from the point of inflow. The absence of varves is a function of the low rates of sediment accumulation and the long residence time of the fine sediments in the water column.Three sediment cores up to 135 cm in length reveal marked changes in sediment characteristics and diatom assemblages through the Holocene. During the late Foxe Glaciation it is likely that glacier ice contacted the lake, with retreat upvalley recorded by thinly varved (?) silts. By 7580 ± 140 BP ice had retreated to near its present margins. The earliest diatom assemblage in the cores is dominated by small Fragilaria spp., typical of late glacial, pioneering environments. Sedimentation rates during much of the Hypsithermal were about five times less than at present, with the resulting massive sediments having "nonglacial" characteristics despite the presence of glacial ice in the drainage basin. A planktonic diatom flora suggests that summer lake ice cover was minimal at this time. A climatic deterioration at about 4500 BP marks the onset of the Neoglacial, recorded by a shift in the diatom assemblage to species characteristic of more shallow water environments. Retreat from Neoglacial moraines is recorded by clearly laminated sediments and increasing accumulation rates. In general, laminated sediments relate to periods of high sediment input associated with glacial retreat, whereas massive sediments relate to low sediment input in association with glacial stabilization or advance.

Relationships among Tubificid Abundances, Sediment Composition, and Accumulation Rates in Lake Erie

1989 ◽  
Vol 46 (2) ◽  
pp. 223-231 ◽  
Author(s):  
J. A. Robbins ◽  
T. Keilty ◽  
D. S. White ◽  
D. N. Edgington
Keyword(s):  
Organic Carbon ◽  
Carbon Flux ◽  
Lake Erie ◽  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Tubifex Tubifex ◽  
Sediment Reworking ◽  
Organic Carbon Flux ◽  
Limnodrilus Hoffmeisteri

Sediment cores taken at 15 sites within the three main depositional basins of Lake Erie from 1976 to 1982 were sectioned in 1-cm intervals and analyzed for the abundance and vertical distribution of benthic organisms, 137Cs, and 210Pb (in some cores) and for surficial (upper 2 cm) organic and inorganic carbon. Zoobenthos populations were dominated (>85%) by tubificids (Limnodrilus hoffmeisteri, Quistadrilus multisetosus, and Tubifex tubifex) and varied in abundance from 6600 to 55 300 individuals∙m−2. The depth above which 90% of the individuals occurred correlated significantly with their abundance and with radiometrically determined mixed depths. Rates of sediment reworking by tubificids exceeded sedimentation rates by 5–80 times, indicating that worms alone can produce the observed zone of constant tracer activity at the sediment–water interface. Tubificid abundance was not significantly related to organic carbon but instead correlated strongly with the sediment accumulation rate and organic carbon flux. In Lake Erie the abundance of tubificids may be limited by the rate of supply of nutrients as measured roughly in terms of the organic carbon flux.

Rates of Sediment Accumulation in Pollen Cores from Small Lakes and Mires of Eastern North America

1988 ◽  
Vol 30 (3) ◽  
pp. 284-297 ◽  
Author(s):  
Robert Stabler Webb ◽  
Thompson Webb
Keyword(s):  
North America ◽  
Accumulation Rate ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Linear Interpolation ◽  
Climatic Conditions ◽  
Eastern North America ◽  
Small Lakes ◽  
Data Set ◽  
Depositional Processes

Data from 291 small lakes and mires in eastern North America provide information on the natural variability of rates of sediment accumulation in these environments over the last 18,000 yr. Accumulation rates were calculated by linear interpolation between radiocarbon and biostratigraphic dates from sediment cores taken for pollen analysis. Within the data set, the rates were lognormally distributed with a mean accumulation rate of 91 cm/103 yr, and a range from less than 1 to over 3500 cm/103 yr. The accumulation rate data were divided into five subsets that were temporally or spatially distinct and therefore represent different geomorphic and climatic conditions at the time of deposition. Sediments deposited in basins north of 50°N, south of 40°N, and before 10,000 yr B.P. accumulated at much slower rates than sediments accumulating in midlatitude basins (between 40° and 50°N) between 10,000 and 330 yr B.P. Sediment accumulation over the last 330 yr has, on average, been at rates four to five times faster than any time previously. Inorganic sediments that could be radiocarbon-dated have accumulated at significantly lower rates than organic sediments, reflecting differences in depositional processes. For midlatitude basins during the Holocene, the most likely rate of continuous sediment accumulation within our data set is 65 cm/103 yr. Rates below 10 cm/103 yr are likely to be associated with nonconstant processes of sediment accumulation.

Paleomagnetic Constraints on Sedimentation Rates in the Eastern Arctic Ocean

1996 ◽  
Vol 46 (1) ◽  
pp. 62-71 ◽  
Author(s):  
David A. Schneider ◽  
Jan Backman ◽  
William B. Curry ◽  
Göran Possnert
Keyword(s):  
Arctic Ocean ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Ocean Basin ◽  
Canada Basin ◽  
Sedimentation Rates ◽  
Carbonate Concentration ◽  
Order Of Magnitude ◽  
Diverse Data

Deep-sea sediments recovered from six sites visited during the International Arctic Ocean Expedition of 1991 were examined to determine sedimentation rates in the eastern Arctic Ocean basin. The dearth of age-diagnostic biogenic material in these sediments precludes the application of biostratigraphic methods, but ages can be deduced using paleomagnetism, in conjunction with measurements of radiocarbon and carbonate concentration. Although no one of these techniques gives an unambiguous determination of age, the interpretation most consistent with these diverse data implies that sedimentation rates in the eastern Arctic are, in general, a few centimeters per thousand years. Such estimates of sedimentation rate are an order of magnitude greater than those previously determined from many sediment cores taken from the Canada Basin. However, one site examined on the Morris Jesup Rise shows a relatively low rate of sediment accumulation (less than 0.6 cm/103 yr) suggesting that, although higher than in the Canada Basin, sedimentation rates in the eastern Arctic can be highly variable.

scholarly journals Fluxes of As, Cu, Hg, Pb in lake sediments in the Coppermine River basin, Canada

2007 ◽  
Vol 38 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Liisa Peramaki ◽  
Michael Stone
Keyword(s):  
Trace Metals ◽  
River Basin ◽  
Anthropogenic Activities ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Temporal Distribution ◽  
Atmospheric Pollutants ◽  
Sedimentation Rates ◽  
Gravity Corer ◽  
Coppermine River

Many watersheds in northern Canada are experiencing increasing pressures from resource extraction, development and the long-range transport of atmospheric pollutants. This study examines sediment accumulation and the spatial and temporal distribution of trace metals in bottom sediment of down gradient lakes in the headwaters of the Coppermine River basin, Canada. Sediment cores were collected from Lac de Gras, Desteffany Lake, Point Lake and Daring Lake using a plastic lined K–B single-gravity corer. Each core was dated using 210Pb and concentrations of trace metals (As, Cu, Hg, Pb) were determined in core sections. Sedimentation rates ranged from 101 g m−2 yr−1 at Desteffany Lake to 156 g m−2 yr−1 at Daring Lake and are comparable to other northern lakes. Concentrations of As and Cu were significantly higher at Lac de Gras. Metal loading data and enrichment ratios show that concentrations of Pb and Hg are elevated compared to historic background levels. Metal enrichment is from anthropogenic activities and atmospheric inputs. Lake sediment represents a good indicator of state for the Coppermine basin and documents historic trends of metal deposition. However, the indicator has low sensitivity to change and coarse temporal resolution due to low sedimentation rates in northern environments.

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