Sedimentation of Pb-210 in Laurentian Shield Lakes

1984 ◽  
Vol 19 (2) ◽  
pp. 97-109 ◽  
Author(s):  
R.J. Cornett ◽  
L. Chant ◽  
D. Link
Keyword(s):  
Lake Sediments ◽  
Water Column ◽  
Rate Constant ◽  
Bottom Sediments ◽  
Atmospheric Fallout ◽  
Small Lakes ◽  
Fractional Rate ◽  
Total Input ◽  
Shield Lakes ◽  
Annual Flux

Abstract The average annual flux of Pb-210 from the atmosphere to lake surfaces and to the bottom sediments was measured in seven small lakes located on the Laurentian Shield. Direct atmospheric fallout of Pb-210 was 136 ± 16 Bq m-2 a-1 Streams from the lakes' catchments input an additional 5 to 473 Bq m-2 a-1. Only 16 to 80 percent of the total input was found in the lake sediments. The fractional rate constant for Pb-210 sedimentation from the water column ranged from 0.25 to 5.3 per annum.

scholarly journals Organochlorine compounds in subarctic small lakes

2020 ◽  
Vol 66 (2) ◽  
pp. 180-197
Author(s):  
E. S. Kolpakova ◽  
A. V. Velyamidova
Keyword(s):  
Lake Sediments ◽  
Bottom Sediments ◽  
Hydrothermal System ◽  
Atmospheric Transport ◽  
Electron Capture Detection ◽  
Adjacent Area ◽  
Chlorinated Phenols ◽  
Natural Boundary ◽  
Small Lakes ◽  
Lake Ecosystems

The article presents the results of studies of the environmental properties of organochlorines which differ in properties and origin, in the lake ecosystems of the Bolshezemelskaya tundra (Nenets Autonomous Okrug, Russia). The purpose of this study was to evaluate and assess the levels, distribution characteristics and composition of organochlorines in the bottom sediments of small lakes located in the Adzva river basin in Pymvashor natural boundary (the northernmost location of the exit of thermal-mineral springs of the continental Europe) and in the adjacent area, outside this unique subarctic hydrothermal zone.In order to meet this goal, multi-method (hydrochemical, geochemical, etc.) research was carried out using standard generally approved laboratory practices with their adaptation to the study goals. The quantitative content and composition of the target individual organochlorines were determined by gas chromatographic method with electron-capture detection.The presence of chlorophenol compounds and polychlorinated benzenes (including persistent organic pollutants) was shown in the lakes sediments. The influence of specific microclimatic conditions of subarctic hydrothermal system on the composition and distribution of chlorophenol compounds in lake sediments was considered. In the small lake sediment core in Pymvashor natural boundary a reducing trend in the levels of organochlorines with depth has been recorded (conditioned among other things by the lithological features of bottom sediments). The chlorophenol compounds were found at highest concentrations (619.3–765.5 ng/g) in the sediment upper layers, rich in organic matter; chlorophenol composition was represented mainly by chlorinated phenols, most likely of biotic origin. A lower concentration (185.0 ng/g) of chlorophenol compounds of predominantly abiogenic origin was determined in the lake sediments outside hydrothermal system. The presence and levels of persistent organochlorine pollutants (pentachlorophenol 0.1–2.4 ng/g; hexa- and pentachlorobenzenes 0.4–3.6 ng/g) in the lake sediments were associated with long-range atmospheric transport from various origin sources in nearby regions and low-latitude territories.

scholarly journals The Micro/elemental Composition of Bottom Sediments of Small Lakes as Indicator of Environmental Risks in Urban Area of Republic of Karelia

2018 ◽  
Author(s):  
Keyword(s):  
Heavy Metals ◽  
Lake Sediments ◽  
Urban Environment ◽  
Bottom Sediments ◽  
Environmental Risks ◽  
Water Bodies ◽  
Individual Species ◽  
Urban Water ◽  
Small Lakes ◽  
Living Organisms

The general questions of the influence of urban environment on the development of deviations in living organisms up to the death of individual species are considered. Using the example of a study of the chemical composition of bottom sediments of six small lakes of the Republic of Karelia, a significant effect of technogenesis on the occurrence of ecological risks on the aquatic flora and fauna of an urbanized environment is shown. We have stated that the upper layers of the bottom sediments of urban lakes have increased concentrations of heavy metals in comparison with the underlying layers. The thickness of technogenically altered lake sediments for urban water bodies of Karelia is established. According to the analysis of the formulas of geochemical associations of bottom sediments of urbanized lakes, we identified priority pollutants (Pb, Sb, Cd, V, Zn, Cu, Ni etc.). These metals are associated with major environmental risks within the urban environment of the region. The patterns of distribution of individual chemical elements in the investigated lake sediments are determined depending on the geochemical specificity of the catchment area and specific sources of heavy metals. Examples of direct negative effects of heavy metals on living organisms of the aquatic environment are benthic organisms and fish. The biogeochemical potential of biota of urban water bodies to accumulate heavy metals and accompanying microelements is shown.

Flora of diatoms of the surface layer of bottom sediments of small lakes of the southeastern part of Belarus

2004 ◽  
Vol 6 (2) ◽  
pp. 186-198
Author(s):  
G. K. Khursevich ◽  
A. V. Kudelskiy ◽  
S. A. Fedenya ◽  
J. Marphy
Keyword(s):  
Surface Layer ◽  
Bottom Sediments ◽  
Small Lakes ◽  
Southeastern Part

Natural and anthropogenic impacts on the composition of lake sediments

2008 ◽  
Vol 72 (1) ◽  
pp. 411-413 ◽  
Author(s):  
T. Eskola ◽  
V. Peuraniemi
Keyword(s):  
World War Ii ◽  
Lake Sediments ◽  
Human Impact ◽  
Catchment Area ◽  
Anthropogenic Impacts ◽  
Heavy Traffic ◽  
World War ◽  
Small Lakes ◽  
Anthropogenic Effect ◽  
The City

AbstractLake sediments were studied from four lakes in environmentally different areas in northern Finland. Lakes Pyykösjärvi and Kuivasjärvi are situated near roads with heavy traffic and the city of Oulu. Lakes Martinlampi and Umpilampi are small lakes in a forest area with no immediate human impact nearby. The concentration of Pb increases in the upper parts of the sedimentary columns of Lake Kuivasjärvi and Lake Pyykösjärvi. This is interpreted as being an anthropogenic effect related to heavy traffic in the area and use of Lake Pyykösjärvi as an airport during World War II. High Ni and Zn concentrations in the Lake Umpilampi sediments are caused by weathered black schists. Sediments in Lake Martinlampi show high Pb and Zn contents with increasing Pb concentrations up through the sedimentary column. The sources of these elements are probably Pb-Zn mineralization in the bedrock, Pb-Zn-rich boulders and anomalous Pb and Zn contents in till in the catchment area of the lake.

Phosphorus Budgets and Stoichiometry during the Open-Water Season in Two Unmanipulated Lakes in the Experimental Lakes Area, Northwestern Ontario

1994 ◽  
Vol 51 (12) ◽  
pp. 2739-2755 ◽  
Author(s):  
P. Campbell
Keyword(s):  
Water Column ◽  
Bottom Sediments ◽  
Open Water ◽  
Short Term ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Phosphorus Budgets ◽  
Mass Balance Approach ◽  
Primary And Secondary Producers ◽  
Column Total

A comparative mass-balance approach is used to describe and quantify phosphorus (P) cycles during the open-water season in two unmanipulated Experimental Lakes Area (ELA) lakes. A bimodal cycle generally prevailed, in which water-column total phosphorus (TP = total dissolved P plus sestonic particulate P) peaked just after ice-out and again late in the summer. Changes in mass of water-column TP were often much larger than corresponding net external inputs. Shifts of P to and from either zooplankton or fish in the water column do not explain the P residuals. Rather, the bottom sediments must have been adding P to the water column. Short-term regeneration of P from the bottom sediments also probably occurs in artificially eutrophied ELA lakes. The mechanism of regeneration is probably biological. Other aspects of P cycling and P stoichiometry are discussed, particularly in relation to nutrient control of population structure and the function of primary and secondary producers.

Effects of Lake Size on Phytoplankton Nutrient Status

1994 ◽  
Vol 51 (12) ◽  
pp. 2769-2783 ◽  
Author(s):  
S. J. Guildford ◽  
L. L. Hendzel ◽  
H. J. Kling ◽  
E. J. Fee ◽  
G. G. C. Robinson ◽  
...  
Keyword(s):  
Nutrient Status ◽  
Canadian Shield ◽  
Small Lakes ◽  
Large Lakes ◽  
P Deficiency ◽  
Water Renewal ◽  
Mixed Layers ◽  
Shield Lakes ◽  
Lake Size ◽  
Total P

Phytoplankton nutrient status measurements (C/P, C/N, C/chlorophyll, N/P, alkaline phosphatase activity, and N debt) were measured for 6 yr in seven remote Canadian Shield lakes. Lakes Nipigon and Superior were also studied for 2 yr. These lakes varied in surface area from 29 to 8.223 × 10 ha, they all stratified fully during the summer and had water renewal times > 5 yr. All lakes were severely P deficient; however, the large lakes (> 2000 ha) were consistently less P deficient than small lakes. A growth-rate indicator (photosynthesis normalized to particulate C) agreed with nutrient status indicators, in that small lakes had lower rates than large lakes. Total P was a good predictor of chlorophyll, but factors related to lake size (temperature and mixed depth) were equally good or better predictors of nutrient status. Decreasing mean water column light intensity could not explain the lower P deficiency of large lakes. The deeper, more energetic mixed layers in large lakes apparently cause P to be recycled more efficiently. Extrapolation of observations or experimental results from small to large lakes requires recognition that phytoplankton in large lakes are less nutrient deficient and may have higher growth rates.

scholarly journals Phosphorus dynamics in sediments of a eutrophic lake derived from 31P nuclear magnetic resonance spectroscopy

2014 ◽  
Vol 65 (1) ◽  
pp. 70 ◽  
Author(s):  
Deniz Özkundakci ◽  
David P. Hamilton ◽  
Richard McDowell ◽  
Stefan Hill
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Water Column ◽  
Bottom Sediments ◽  
Eutrophic Lake ◽  
Resonance Spectroscopy ◽  
31P Nmr Spectroscopy ◽  
31P Nuclear Magnetic Resonance ◽  
Lake Okaro ◽  
Nuclear Magnetic

The determination of organic phosphorus (P) compounds in lake sediments can provide information on the potential for internal P loading. Settling seston and vertical sediment core samples from highly eutrophic Lake Okaro, New Zealand, were collected during a mixed winter and stratified summer period, representing, respectively, when the water column was well oxygenated and when the bottom waters were anoxic. Samples were analysed with 31P nuclear magnetic resonance (31P NMR) spectroscopy, which showed that both bottom sediments and settling seston contained orthophosphate, orthophosphate monoesters and diesters, pyrophosphates, polyphosphates and phosphonates. Phosphorus concentration in settling seston increased ~2.5-fold in winter as a result of seasonally induced changes in phytoplankton biomass, with a marked increase in the concentration of orthophosphate. Several potentially bioavailable P compounds in the bottom sediments were identified that were likely to contribute to recycling of P from the sediment to the water column. An ‘apparent half-life’ was used to quantify the time scales on which these compounds were recycled to the overlying water column. Orthophosphate monoesters that include inositol phosphates were the most persistent P compound. On the basis of half-lives, high internal P loadings may persist for more than 20 years, potentially hindering restoration efforts in Lake Okaro.

scholarly journals Rumen fill and digesta kinetics in lactating Friesian cows given two levels of concentrates with two types of grass silage ad lib

1991 ◽  
Vol 66 (3) ◽  
pp. 381-398 ◽  
Author(s):  
J. Gasa ◽  
K. Holtenius ◽  
J. D. Sutton ◽  
M. S. Dhanoa ◽  
D. J. Napper
Keyword(s):  
Particle Size ◽  
Rate Constant ◽  
Rumen Fluid ◽  
Latin Square ◽  
Grass Silage ◽  
Fractional Rate ◽  
Fibre Degradation ◽  
Kinetics Of ◽  
Resting Period ◽  
Friesian Cows

Four lactating Friesian cows with permanent cannulas in the rumen and proximal duodenum were given early (EC)- or late (LC)-cut grass silage ad lib., each with either 3 or 9 kg concentrate dry matter (DM)/d in a 4 x 4 Latin square design starting about 10 weeks after calving. Feed was offered twice daily at 08.30 hours and 15.30 hours. Periods lasted 5 weeks and measurements were made in the last 15 d. The higher amount of concentrates increased total DM intake but reduced silage DM intake and the fractional rate of degradation of silage-fibre DM. Later cutting date of silage had no effect on DM intake or the fractional rate of degradation of silage-fibre DM but reduced potential degradability of silage fibre. Dilution rate of CoEDTA in rumen fluid was greater during the day (eating period) than during the night (resting period). Dilution rates measured at the duodenum were lower than those measured in the rumen, but neither was affected by diet. Silage-particle passage rates were measured by use of ytterbium-labelled silage fibre (Yb-fibre) and chromium-mordanted faecal particles (Cr-faeces) and samples were taken at the duodenum and in the faeces. Values for slower rate constant (k1) and transit time were higher and for faster rate constant (k2) were lower for Yb-fibre than for Cr-faeces, but differences in total mean retention time were inconsistent. Values for k1 for both markers and k2 for Yb-fibre only were similar at both sampling sites, but values for k2 for Cr-faeces were lower in the faeces. No diet effects were established with Yb-fibre but, with Cr-faeces, k1 was reduced by more concentrates and EC-silage. Daily mean weights of wet digesta, liquid, neutral-detergent fibre (NDF) and indigestible NDF in the rumen were greater with LC-silage but were unaffected by the amount of concentrates whereas weight of rumen DM was increased by the amount of concentrates only. Maximum rumen fill occurred at 18.00 hours with all diets. Particle-size distribution of rumen contents did not vary markedly during the day. Mean particle size was generally greater with LC-silage than EC-silage. Very small particles, passing through the 0.3 mm screen, constituted about half the rumen DM. It is concluded that rumen fill could have limited intake of LC-silage but not EC-silage. The reduced silage intake with greater concentrate intake was associated with a reduction in fibre degradation rate and an increase in rumen DM fill but no other consistent effects on weight or kinetics of rumen fractions were established.

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