Measurement of Whole Lake Sediment Accumulation and Phosphorus Retention Using Lead-210 Dating

1980 ◽  
Vol 37 (5) ◽  
pp. 817-822 ◽  
Author(s):  
R. Douglas Evans ◽  
Frank H. Rigler
Keyword(s):  
Sediment Accumulation ◽  
Lake Area ◽  
Phosphorus Retention ◽  
Sediment Retention ◽  
Sample Depth ◽  
Highly Correlated ◽  
Lead 210 ◽  
Mean Concentration ◽  
Measured Input ◽  
Rate Of Accumulation

Lead-210 dating was used to measure rates of sediment accumulation in 15 cores from Bob Lake, Ontario. The rate of accumulation was highly correlated with sample depth. This relation allowed the calculation of accumulation of sediments over the whole lake area. Phosphorus (P) retention was calculated from mean concentration of P in the sediments and the whole lake accumulation of sediment. Retention of P calculated in this way was similar to retention calculated from previously measured input and output of P.Key words: lead-210 dating, sediment accumulation, phosphorus retention

scholarly journals 240+239Pu depositional signatures as a viable geochronological tool in the Amazon Basin

2017 ◽  
Vol 44 (1) ◽  
pp. 142-149 ◽  
Author(s):  
Luciana M Sanders ◽  
Kathryn H Taffs ◽  
Debra Stokes ◽  
Alex Enrich-Prast ◽  
Christian J Sanders
Keyword(s):  
Amazon Basin ◽  
Environmental Science ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Recent Sediment ◽  
Floodplain Lake ◽  
Accumulation Rates ◽  
Amazon Floodplain ◽  
Dating Methods ◽  
Lead 210

AbstractAnthropogenic radionuclide signatures associated with nuclear testing are increasingly utilized in environmental science to explore recent sedimentation. In this study, we assess the suitability of Pu radioisotope analysis in floodplain lake environments in the Amazon Basin to form geochronologies during the 20thcentury. The240Pu +239Pu (240+239Pu) signatures in six sediment cores indicate sediment accumulation rates in the floodplain lakes of the major rivers; Amazon (2.3 mm year-1), Tapajos (10.2 and 2.4 mm year-1) and Madeira (3.4, 4.2 and 6.2 mm year-1). The results from this study show that240+239Pu fallout activities, and the well documented (240Pu/239Pu) atomic ratios of the above ground nuclear tests which began in the 1950’s, are sufficient and well preserved in Amazon floodplain lake sediments to infer chronologies. Lead-210 dating analyses in the same sediment cores produced comparable sediment accumulation rates at three of the six sites. The differences between dating methods may be attributed to the different time scale these dating methods represent and/or in the solubility between Pb and Pu along the sediment column. The geochronologies derived from the240+239Pu and210Pb dating methods outlined in this work are of interest to identify the effects of changing sediment accumulation rates during the previous century as a result of development, including deforestation, along the Amazon Basin which increased towards the middle of the 20thcentury. This study shows that Pu dating provides a viable alternative geochronology tool for recent sediment accumulation (previous ~60 years) along the Amazon Basin.

Reconstructing the Rate of Accumulation of Lake Sediment: The Effect of Sediment Focusing

1975 ◽  
Vol 5 (4) ◽  
pp. 541-550 ◽  
Author(s):  
John T. Lehman
Keyword(s):  
Temporal Variation ◽  
Lake Sediment ◽  
Sediment Cores ◽  
Sediment Accumulation ◽  
Maximum Depth ◽  
Accumulation Rates ◽  
Sediment Focusing ◽  
Regional History ◽  
Rate Of Accumulation

Use of accumulation rates of pollen or minerals to infer regional history is complicated by nonuniform deposition of lake sediment. Sediment focusing, direction of sediment to the deepest part of a basin, can introduce a discrepancy between changes in accumulation rates measured directly from sediment cores and actual changes in influx of sediment or pollen to a lake. This difference depends on values and temporal variation of the ratio of mean depth to maximum depth in a basin as it fills. Several models of sediment accumulation show how measurements from a single core can be transformed to yield basinwide influx rates, and how the distortion due to sediment focusing can be assessed. Basins shaped like hyperboloids or frustums may introduce much greater distortions than basins conforming to ellipsoid or sinusoid shapes.

Lead-210 chronology of the Scandinavian SWAP sites

1990 ◽  
Vol 327 (1240) ◽  
pp. 239-242 ◽  
Keyword(s):  
Land Use ◽  
Sediment Accumulation ◽  
Past Century ◽  
The Past ◽  
Enhanced Dissolution ◽  
Surface Water Acidification ◽  
Constant Rate ◽  
Minor Losses ◽  
Lead 210 ◽  
Atmospheric Inputs

In the Surface Water Acidification Project (SWAP) sediment profiles from five Scandinavian sites were analysed for 210 Pb by using refined isotope dilution alpha spectrometry. The 210 Pb parameters of these lakes were very similar to those obtained for protected forest lakes with no land-use activities. These data demonstrated almost exclusive atmospheric inputs and an internal deposition regulated by the organic fractionation and the grain-size distribution in the sediments. Preliminary speciation experiments showed minor losses of 210 (≤ 5%) through enhanced dissolution of fulvic compounds at acid conditions (pH ≥ 4). The sediment accumulation rates (constant rate of unsupported 210 Pb supply (CRS) model) of the lakes gradually increased, by at least a factor of three, over the past century although 210 Pb parameters did not show any strong signs of enhanced land-use activities. This is perhaps caused by more efficient preservation of the sediments through humic precipitation under more acid conditions.

Reproductive Seasonality in Female Platypuses, Ornithorhynchus anatinus, in the Upper Barnard River, New South Wales.

1998 ◽  
Vol 20 (2) ◽  
pp. 207
Author(s):  
J.M. Jakubowski ◽  
N.P. New ◽  
G.M. Stone ◽  
R.C. Jones
Keyword(s):  
Blood Plasma ◽  
Seasonal Change ◽  
Coefficient Of Variation ◽  
New South ◽  
Reproductive Seasonality ◽  
South Wales ◽  
Ornithorhynchus Anatinus ◽  
Highly Correlated ◽  
Change In Mean ◽  
Mean Concentration

Progesterone concentrations were determined in samples of blood, urine and faeces collected from female platypuses which were captured in the Upper Barnard River, NSW, from February to November, 1996. Mean concentrations in blood plasma were higher in July, August and September than in other months with the highest concentrations being in August. Progesterone concentrations in dried urine and faeces were highly correlated with values for blood plasma (r = 0.61, P<0.05 and 0.7 1, P<O.OI, respectively), and the coefficient of variation for progesterone determinations was lower for samples of urine and faeces than blood. There was a seasonal change in mean concentration of cortisol in blood (being elevated in May-August), but the concentrations of progesterone and cortisol in blood were not significantly correlated.

A Test of Lead-210 Dating for the Measurement of Whole Lake Soft Sediment Accumulation

1983 ◽  
Vol 40 (4) ◽  
pp. 506-515 ◽  
Author(s):  
R. Douglas Evans ◽  
Frank H. Rigler
Keyword(s):  
Lake Sediment ◽  
Accumulation Rate ◽  
Sediment Accumulation ◽  
Soft Sediment ◽  
Lake Morphometry ◽  
Southern Ontario ◽  
Lake Bottom ◽  
Lead 210 ◽  
Shield Lakes ◽  
The Relationship

We have tested the hypothesis that variation in accumulation of soft sediments over a lake bottom is related to the lake morphometry, allowing an accurate measurement of whole lake sediment accumulation. In each of two Laurentian Shield lakes in southern Ontario, sediment accumulation was measured at ~20 locations. In both there was a statistically significant linear relationship between soft sediment accumulation and the water depth at the sample locations. The relationship explained 72 and 57% of sediment accumulation variation in Costello and Red Chalk lakes, respectively. Using these relationships, it was possible to calculate the whole lake sediment accumulation rate for each lake. The results indicate that, in general, there is a linear variation in sediment accumulation as a function of depth in small Shield lakes. This study points out the need for a closer examination of sediment movement and accumulation in the shallow regions of lakes.

Sedimentology of the Permian Radok Conglomerate in the Beaver Lake area of MacRobertson Land, East Antarctica

1995 ◽  
Vol 132 (1) ◽  
pp. 51-63 ◽  
Author(s):  
C. R. Fielding ◽  
J. A. Webb
Keyword(s):  
Sediment Accumulation ◽  
East Antarctica ◽  
Upper Permian ◽  
Rift System ◽  
Flow Sheet ◽  
Lake Area ◽  
Organic Sediment ◽  
Sediment Gravity Flow ◽  
Beaver Lake ◽  
Coal Measures

AbstractThe mid- to Upper Permian Radok Conglomerate, the lowermost formation of the Permo-Triassic Amery Group, crops out in the Beaver Lake area of the northern Prince Charles Mountains, East Antarctica. Outcrop is confined to a north-south elongate, fault-bounded corridor interpretedas a remnant of a continental extensional basin formed during Late Palaeozoic times. This basinforms a small part of the much larger Lambert Graben, a major continental rift system. The RadokConglomerate consists of interbedded conglomerates, argillaceous sandstones, siltstones, and minor, thin carbonaceous siltstones and coals. Textural, petrographic, palaeocurrent and other data suggestlocal derivation from Precambrian massifs to the immediate west, during a period of fault activity.The unit is a minimum of 400 m thick, the base being unexposed, and grossly fines upward. It isabruptly overlain by quartzo-feldspathic sandstone-dominated rocks of the Upper Permian Bainmedart Coal Measures. Seven recurrent lithofacies have been recognized with the Radok Conglomerate, and are interpreted as the products of poorly-confined stream flow, sheet flow and sediment gravity flow processes, suspension fallout in shallow standing water, and organic sediment accumulation in peat-forming wetlands. The unit as a whole is interpreted as having accumulated as a coarse alluvial apron along the western margin of a ?graben extensional trough. Similar, though poorly exposed, facies are exposed on the eastern margin of the basin and may reflect similar depositional systems. Towards the top of the Radok Conglomerate, typical Radok lithologies are interbedded with quartzo-feldspathic sandstones derived from the south, precursors of the overlying Bainmedart Coal Measures. Interference between transverse (Radok) and axial (Bainmedart) drainage is possibly related to progressive infilling of extensional topography, thereby allowing axially flowing rivers to avulse increasingly into the Beaver Lake region from the main Lambert Graben.

scholarly journals Phosphorus retention in drainage soils of commercial greenhouses.

1969 ◽  
Vol 95 (1-2) ◽  
pp. 1-14
Author(s):  
José A. Dumas ◽  
Joaquín A. Chong ◽  
Magaly Cintrón ◽  
Luis Reinaldo Santiago
Keyword(s):  
Phosphorus Retention ◽  
Organic Residues ◽  
Soil Factors ◽  
Retention Capacity ◽  
Soil P ◽  
Al Content ◽  
P Concentration ◽  
Highly Correlated ◽  
Retention Parameters ◽  
P Retention

Five commercial greenhouses in the central mountainous zone of Puerto Rico were studied in order to identify changes in soil factors that affect P retention. Soils were collected both within and outside drainages at a 0- to 15-cm depth. Soil physicochemical properties varied in samples taken both within and outside drainages. The high Fe and Al content in the soils of this study suggested a high phosphorus retention capacity. Laboratory estimates of P retention parameters indicated differences in P sorption capacity among soils. Phosphorus retention parameters were highly correlated with citrate dithionite extractable Fe. The equilibrium P concentration was also correlated with citrate dithionate Al in soils outside drainages. This finding was due to the higher soil organic matter counterbalancing the soil P retention capability of Al, all of which indicates the importance of clearing all drainages of organic residues in order to avoid excessive movement of P outside the greenhouse premises.

scholarly journals A Population-Based Threshold of Protection for COVID-19 Vaccines

2021 ◽  
Author(s):  
David Goldblatt ◽  
Andrew Fioré-Gartland ◽  
Marina Johnson ◽  
Adam Hunt ◽  
Christopher Bengt ◽  
...  
Keyword(s):  
Geometric Mean ◽  
Population Based ◽  
Correlates Of Protection ◽  
Proven Efficacy ◽  
The Mean ◽  
Alpha Variant ◽  
Highly Correlated ◽  
Protective Threshold ◽  
Mean Concentration ◽  
Original Virus

Abstract Correlates of protection for COVID-19 vaccines are urgently needed to license and deploy additional vaccines. We measured immune responses to four COVID-19 vaccines of proven efficacy using a single serological platform calibrated to the international standard. IgG anti-Spike antibodies correlated significantly with efficacies for original virus and alpha variant and were highly correlated with ID50 neutralization in a validated pseudoviral assay. The protective threshold for each vaccine was calculated for IgG anti-Spike antibody. The mean protective threshold for all vaccine studies was 154 BAU/ml (95%CI 42-559), and for the vaccine studies with antibody distributions that enabled precise estimation of thresholds (i.e. leaving out 2-dose mRNA studies) was 60 BAU/ml (95%CI 35-102). We propose that the proportion of individuals with responses above the appropriate protective threshold together with the geometric mean concentration can be used in comparative non-inferiority studies with licensed vaccines to ensure that new vaccines will be efficacious.

Polonium-210 in cartilaginous fishes (Chondrichthyes) from south-eastern Australian waters

1993 ◽  
Vol 44 (5) ◽  
pp. 727 ◽  
Author(s):  
JD Smith ◽  
PH Towler
Keyword(s):  
Absorbed Dose ◽  
Naturally Occurring ◽  
Elasmobranch Species ◽  
Wet Weight ◽  
The Mean ◽  
Concentration Factors ◽  
Cartilaginous Fishes ◽  
Lead 210 ◽  
Mean Concentration

A study was made of the concentration of the naturally occurring radionuclide polonium-210 in the livers of cartilaginous fishes (chondrichthyans) caught in the waters of Port Phillip Bay, Victoria, Australia in 1991. Five elasmobranch species had 210Po concentrations in the range 1-31 Bq kg-1 (wet weight) and one holocephalian species, the elephant fish (Callorhynchus milii), was exceptional with a 210Po range of 60-270 Bq kg-1 (n=3, mean 180 Bq kg-1). Lead-210 was present at 0.1- 1.1 Bq kg-1 and activity concentration ratios of 210Po:210Pb were all greater than 1, indicating that the 210Po could not all have grown in from in situ decay of 210Pb within the chondrichthyan liver. The concentration of 210Po in the livers appeared to be species related. Concentrations of the trace metals Cu, Fe and Zn showed no correlation with the 210Po and were not species-related. The mean concentration of 210Po measured in Port Phillip Bay water was 0.32 mBq kg-1. This yields concentration factors of 3.2 × 103 to 8.4 × 105 for unsupported 210Po in the livers of the chondrichthyans. The total 210Po (using Q=20) exposes the livers to a weighted absorbed dose of up to 140 mGy year-1 (16�Gy h-1), which is >99% of the total internal dose and three orders of magnitude greater than the external dose based on estimated levels of 40K.

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