Modelling of 210Pb behaviour in the catchment and sediment of Lake Tali Karng, Victoria, and estimation of recent sedimentation rates.

1985 ◽  
Vol 36 (1) ◽  
pp. 15 ◽  
Author(s):  
JD Smith ◽  
TF Hamilton
Keyword(s):  
Lake Sediment ◽  
Sediment Core ◽  
Sedimentation Rate ◽  
Average Rate ◽  
210Pb Dating ◽  
Sedimentation Rates ◽  
Depth Profiles ◽  
Unsupported 210Pb ◽  
210Pb Activity ◽  
Over Time

The technique of 210Pb dating of sediments over time scales of up to 120 years is described and illustrated by a study of Lake Tali Karng. Results from the study of a sediment core from the deepest part of the lake shows that the flux of unsupported 210Pb to the sediment is about 145 mBq cm-2 year-1. Over the last 100 years, about 75 cm of sediment has accumulated at an average rate of 150-200 mg cm-2 year-1. Calculations using two models to convert 210Pb activity-depth profiles to age-depth profiles indicate that the sedimentation rate has increased slightly over the last 100 years. It is estimated that about 14% of the 210Pb falling in the catchment reaches the lake sediment, but depending on the assumptions made the possible range is 7-60%.

The determination of sedimentation rates in Lake Ontario using the 210Pb dating method

1978 ◽  
Vol 15 (3) ◽  
pp. 431-437 ◽  
Author(s):  
John G. Farmer
Keyword(s):  
Sedimentation Rate ◽  
Lake Ontario ◽  
Sedimentary Basins ◽  
210Pb Dating ◽  
Sedimentation Rates ◽  
Surface Mixing ◽  
Dating Method ◽  
210Pb Dating Method

The 210Pb dating method has been applied successfully to the determination of recent sedimentation rates at four sites distributed among the three major sedimentary basins (Niagara, Mississauga and Rochester) of Lake Ontario. Following correction for effects due to compaction of the sediments, mean sedimentation rates ranging from 0.02 cm/year at the periphery of the Mississauga basin to 0.11 cm/year in the Niagara and Rochester basins were determined. Allowance for compaction reduced the non-compaction-corrected sedimentation rates by 20–35%. Neither 210Pb nor fallout 137Cs profiles indicated surface mixing of sediment sufficient to noticeably affect the calculated sedimentation rates. At all four sites, the sedimentation rate seems to have remained constant during the last 100–150 years.

scholarly journals Quantification of tantalum sedimentation rates in liquid embolic agents

2018 ◽  
Vol 24 (5) ◽  
pp. 574-579 ◽  
Author(s):  
JR Mason ◽  
C Dodge ◽  
G Benndorf
Keyword(s):  
Sedimentation Rate ◽  
Arteriovenous Malformations ◽  
Sedimentation Rates ◽  
Signal To Noise ◽  
X Ray ◽  
Time Points ◽  
Embolic Agents ◽  
Covalently Bonded ◽  
Liquid Embolic ◽  
Over Time

Background Endovascular treatment (EVT) of brain arteriovenous malformations has evolved from cyanoacrylate derivatives such as N-butyl cyanoacrylate, an adhesive glue, to ethylene vinyl copolymer-based liquid embolics such as Onyx® and SQUID® dissolved in dimethyl sulfoxide. Although these agents offer several advantages, their rapidly decreasing radiopacity, as a result of the sedimentation of tantalum powder, compromises visual control during EVT. This study aims to quantify and compare tantalum sedimentation rates of several liquid embolic agents, and determine their effects on radiopacity. Methods The rate of sedimentation of liquid embolics Onyx 18®, SQUID 12®, and SQUID 18® was measured after preparation by single x-ray exposures for a period of 30 minutes. The signal-to-noise ratios (SNRs) of the suspension of each liquid embolic was calculated at various time points as tantalum settled out of the suspension. Precipitating Hydrophobic Injectable Liquid (PHIL®) was imaged as a control. Results Onyx 18® demonstrated the fastest sedimentation rate of the liquid embolics analyzed and demonstrated a threefold faster drop in SNR compared to SQUID 18® over 30 minutes. Onyx 18® demonstrated a one and a half times faster drop in SNR compared to SQUID 12®. Although PHIL 25® maintained constant SNR over the same time, it was lower at baseline immediately after preparation compared to tantalum-based liquids. Conclusion Caution during long injections using tantalum-based agents is advised. Onyx 18® has a significantly faster drop in radiopacity compared to SQUID 12® and SQUID 18®. Covalently bonded iodine-based embolics like PHIL® demonstrate constant radiopacity over time.

scholarly journals Study on Vertical Profile of 210Pb and Sedimentation Rate at Pantai Remis Coastal Area and Kuala Selangor Estuary

2018 ◽  
Vol 7 (3.11) ◽  
pp. 202
Author(s):  
Umi Kalsum Abdul Karim ◽  
Ahmad Saat ◽  
Mohamed Izzharif Abdul Halim
Keyword(s):  
Sedimentation Rate ◽  
Coastal Area ◽  
Vertical Profile ◽  
Sediment Cores ◽  
210Pb Dating ◽  
Gravity Corer ◽  
210Pb Activity ◽  
Constant Rate ◽  
High Sedimentation ◽  
High Sediment

Two sediment cores in Kuala Selangor estuary and Pantai Remis coastal area were obtained using gravity corer and then were analyzed using Alpha Spectrometry System. In order to estimate the sedimentation rate in the area, 210Pb dating technique and Constant Rate & Supply (CRS) model were used. From the study, the vertical profile of 210Pb shows a decreasing trend with depth and finally achieving a constant level. Based on the vertical profile of 210Pb, activity of excess 210Pb was obtained and was used to determine the sedimentation rate in the study area. Pantai Remis coastal area shows high sedimentation rate than Kuala Selangor estuary which may due to high sediment input in the area. Besides, the differences in sedimentation rate might be attributed to highly variable sedimentary and hydrodynamic conditions in the estuary and coastal area.  

A 450-year warming and wetting climate in southern Altay inferred from a Yileimu Lake sediment core

2021 ◽  
Author(s):  
Jiawei Fan ◽  
Hanchao Jiang ◽  
Wei Shi ◽  
Qiaoqiao Guo ◽  
Siqi Zhang ◽  
...  
Keyword(s):  
Lake Sediment ◽  
Sediment Core ◽  
Lake Sediment Core

Lake Sediment Core Records of Sulphur Accumulation and Sulphur Isotopic Composition in Central Ontario, Canada Lakes

2006 ◽  
Vol 35 (1) ◽  
pp. 99-109 ◽  
Author(s):  
M. Catherine Eimers ◽  
Andrew M. Paterson ◽  
Peter J. Dillon ◽  
Sherry L. Schiff ◽  
Brian F. Cumming ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Lake Sediment ◽  
Sediment Core ◽  
Lake Sediment Core ◽  
Sulphur Isotopic Composition

scholarly journals Lithium carbonate sedimentation using flocculants with different ionic bases

2021 ◽  
pp. 20-20
Author(s):  
Yam Morales ◽  
Nelson Herrera ◽  
Kevin Pérez
Keyword(s):  
Sedimentation Rate ◽  
Rapid Growth ◽  
Crystallization Process ◽  
Lithium Carbonate ◽  
Rechargeable Batteries ◽  
Point Of View ◽  
Sedimentation Rates ◽  
Economic Point ◽  
Carbonate Sedimentation ◽  
Cationic Flocculant

Lithium has become a metal of enormous interest worldwide. The extensive use of rechargeable batteries for a range of applications has pushed for rapid growth in demand for lithium carbonate. This compound is produced by crystallization, by reaction with lithium chloride (in solution) and by adding sodium carbonate. Low sedimentation rates in the evaporation pools present a problem in the crystallization process. For this reason, in this work, mineral sedimentation tests were carried out with the use of two flocculant types with different ionic charges. The tests were carried out at a laboratory level using different dosages for each flocculant and measurements were performed to obtain the increase in the content of solids in the sediment. The anionic flocculant had better performance as compared to that of the cationic flocculant, increasing the sedimentation rate of lithium carbonate by up to 6.5. However, similar solids contents were obtained with the use of the cationic flocculant at 3.5 times lower dosage making it the flocculant of choice regarding the economic point of view.

scholarly journals Chitinase Genes in Lake Sediments of Ardley Island, Antarctica

2005 ◽  
Vol 71 (12) ◽  
pp. 7904-7909 ◽  
Author(s):  
Xiang Xiao ◽  
Xuebin Yin ◽  
Jian Lin ◽  
Liguang Sun ◽  
Ziyong You ◽  
...  
Keyword(s):  
Bacterial Community ◽  
Lake Sediment ◽  
Sediment Core ◽  
Chitinase Gene ◽  
16S Rrna Genes ◽  
Rrna Genes ◽  
Chitinolytic Bacteria ◽  
Organic Carbon Concentration ◽  
Gene Copies ◽  
Chitinase Genes

ABSTRACT A sediment core spanning approximately 1,600 years was collected from a lake on Ardley Island, Antarctica. The sediment core had been greatly influenced by penguin guano. Using molecular methods, the chitinolytic bacterial community along the sediment core was studied over its entire length. Primers targeting conserved sequences of the catalytic domains of family 18 subgroup A chitinases detected group A chitinases from a wide taxonomic range of bacteria. Using quantitative competitive PCR (QC-PCR), chitinase gene copies in each 1-cm section of the whole sediment column were quantified. QC-PCR determination of the chitinase gene copies indicated significant correlation with phosphorus and total organic carbon concentration, suggesting a historical connection between chitinase gene copies and the amount of penguin guano input into the lake sediment. Most of the chitinase genes cloned from the historic sediment core were novel. Analysis of the chitinase gene diversity in selected sediment layers and in the fresh penguin deposits indicated frequent shifts in the chitinolytic bacterial community over time. Sequence analysis of the 16S rRNA genes of chitinolytic bacteria isolated from the lake sediment revealed that the isolates belonged to Janthinobacterium species, Stenotrophomonas species of γ-Proteobacteria, Cytophaga species of the Cytophaga-Flexibacter-Bacteroides group, and Streptomyces and Norcardiopsis species of Actinobacteria. Chitinase gene fragments were cloned and sequenced from these cultivated chitinolytic bacteria. The phylogeny of the chitinase genes obtained from the isolates did not correspond well to that of the isolates, suggesting acquisition via horizontal gene transfer.

Taphonomy and paleoecology of the bivalve trace fossil Protovirgularia in deltaic heterolithic facies of the Miocene Chenque Formation, Patagonia, Argentina

2010 ◽  
Vol 84 (4) ◽  
pp. 730-738 ◽  
Author(s):  
Noelia B. Carmona ◽  
María Gabriela Mángano ◽  
Luis A. Buatois ◽  
Juan José Ponce
Keyword(s):  
Sedimentation Rate ◽  
Oxygen Depletion ◽  
Sedimentation Rates ◽  
Low Friction ◽  
Delta Front ◽  
Plastic Substrates ◽  
Marine Deposits ◽  
Median Axis ◽  
Nearshore Environments ◽  
Biogenic Structures

Lower Miocene tide-influenced deltaic deposits from the Chenque Formation, Patagonia, Argentina, contain abundant and well-preserved biogenic structures attributed to locomotion of deposit-feeder protobranch bivalves. These trace fossils, assigned to the ichnogenus Protovirgularia, consist of delicate, inclined-to-horizontal, chevronate structures, mostly symmetrical with respect to a median axis. Identification of Protovirgularia at sandstone sole beds (hypichnion) is quite straightforward. Endichnial, exichnial and epichnial preservation in heterolithic facies, however, provides a wide variety of forms that depart from the archetypal Protovirgularia and challenges ichnotaxonomic classification. Specimens in prodelta and delta-front facies display morphologic features controlled by substrate fluidity, toponomy, and sedimentation rate. Most specimens show sharp, closely spaced chevrons and occur along sandstone/mudstone interfaces of the proximal prodelta and distal delta-front deposits. These forms reflect how tracemakers experienced significant friction while advancing through the sediment, which resulted in relatively smaller increments of movements. In contrast, variants of Protovirgularia formed in muddier beds, such as in prodeltaic facies, show irregular, poorly defined and unevenly spaced chevrons, and are locally asymmetric in relation to the axis, reflecting softer, water-rich, and plastic substrates. This sediment offered relatively low friction but poor anchorage for the foot. These occurrences of Protovirgularia in tide-influenced, marginal-marine deposits suggests that protobranchs were tolerant of fluctuations in salinity, sedimentation rates, turbidity, and oxygen depletion, displaying opportunistic strategies in stressed nearshore environments. Our evaluation of taphonomic controls and appropriate identification of Protovirgularia can provide valuable information for expanding our knowledge of the ethology and paleoecology of protobranch bivalves.

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