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.

Bioavailability of Polychlorinated Dibenzo-p-dioxins in Lake Enclosures

1992 ◽  
Vol 49 (4) ◽  
pp. 735-742 ◽  
Author(s):  
Mark R. Servos ◽  
Derek C. G. Muir ◽  
G. R. Barrie Webster
Keyword(s):  
Water Column ◽  
Food Chain ◽  
Chain Model ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Sediment Slurry ◽  
Food Chain Model ◽  
Food Chain Transfer ◽  
Kinetics Of ◽  
Detrital Food Chain

The bioavailability of 1,3,6,8-tetra- (T4CDD) and octachlorodibenzo-p-dioxin (O8CDD) was examined in large (40 m3) lake enclosures at the Experimental Lakes Area in northwestern Ontario. The polychlorinated dioxins (PCDDs) were added to replicate enclosures as a sediment slurry at a nominal concentration of 58–59 ng∙L−1. T4CDD was more bioavailable to caged benthic invertebrates and fish (white sucker, Catostomus commersoni) than O8CDD immediately after the addition to the enclosures. However, as the concentration of T4CDD in the water column rapidly declined, the bioavailability of T4CDD also declined. Sorption of PCDD to organic matter and rapid partitioning to sediments might have reduced the uptake of PCDDs directly from the water column. Accumulation of PCDDs in biota appeared to shift from direct equilibrium partitioning during the first few days, when the concentrations in the water column were relatively high, to a detrital food chain transfer as the freely available PCDDs in the water declined. This conclusion is supported by the results of the simple, four-compartment food chain model of Thomann and Connolly based on the uptake kinetics of PCDDs from water and food.

Environmental Fate of Polychlorinated Dibenzo-p-dioxins in Lake Enclosures

1992 ◽  
Vol 49 (4) ◽  
pp. 722-734 ◽  
Author(s):  
Mark R. Servos ◽  
Derek C. G. Muir ◽  
G. R. Barrie Webster
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Particulate Organic Matter ◽  
Environmental Fate ◽  
Aquatic Environments ◽  
Surficial Sediments ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Chlorine Substitution ◽  
Sediment Slurry

The environmental fate of 1,3,6,8-tetra- (T4CDD) and octachlorodibenzo-p-dioxin (O8CDD), two major dioxin congeners emitted into the environment, was studied in large (40 m3) lake enclosures at the Experimental Lakes Area in northwestern Ontario. The polychlorinated dioxins (PCDDs) were added to replicate enclosures as a sediment slurry at a nominal concentration of 58–59 ng∙L−1. Both congeners partitioned/settled rapidly to the surficial sediments where they persisted over the 2 yr of the study. Initially the concentrations of the T4CDD in water were higher than those of O8CDD, but the concentrations of the T4CDD in the water column declined more rapidly than those of O8CDD, with t1/2 of 2.6 ± 0.2 and 4.0 ± 0.3 d, respectively. Approximately 10–15% of the T4CDD and < 1% of the O8CDD detected in the water column during the first 48 h were determined to be truly dissolved. The rapid partitioning of O8CDD and to a lesser extent T4CDD to dissolved and particulate organic matter in the water column and sediments limited their bioavailability. Increased retentive capacity of the higher chlorinated PCDDs may explain the pattern of increasing concentration of PCDDs in sediments with increasing chlorine substitution observed in the Great Lakes and other aquatic environments.

Benthic algal biomass — measurement and errorsThis paper is part of the series “Forty Years of Aquatic Research at the Experimental Lakes Area”.

2009 ◽  
Vol 66 (11) ◽  
pp. 1989-2001 ◽  
Author(s):  
Helen M. Baulch ◽  
Michael A. Turner ◽  
David L. Findlay ◽  
Rolf D. Vinebrooke ◽  
William F. Donahue
Keyword(s):  
Chlorophyll A ◽  
Rocky Mountains ◽  
Algal Biomass ◽  
Experimental Studies ◽  
High Variability ◽  
Algal Community ◽  
Canadian Rocky Mountains ◽  
Short Term ◽  
Experimental Lakes Area ◽  
Northwestern Ontario

While benthic algal biomass is one of the most commonly measured variables within littoral communities, it is also one of the most poorly characterized. The use of chlorophyll a as an estimate of biomass, while easy and inexpensive, can be affected by changes in environmental conditions and algal community composition. Biovolume-based measurements often have high variability and are affected by changes in cell volume due to preservation. Using 12 years of data from the Experimental Lakes Area (northwestern Ontario, Canada) as well as short-term surveys and experimental studies from the Experimental Lakes Area and the Canadian Rocky Mountains, we demonstrate that biovolume and chlorophyll a are often decoupled in the littoral zone of temperate oligotrophic lakes. We recommend that researchers revisit the limitations of both metrics and specifically caution against the use of chlorophyll a as a biomass indicator when light, temperature, or species composition vary significantly.

Measurements of Specific Rates of Net Methyl Mercury Production in the Water Column and Surface Sediments of Acidified and Circumneutral Lakes

1987 ◽  
Vol 44 (4) ◽  
pp. 750-757 ◽  
Author(s):  
Luying Xun ◽  
N. E. R. Campbell ◽  
John W. M. Rudd
Keyword(s):  
Water Column ◽  
Water Samples ◽  
Methyl Mercury ◽  
Lake Acidification ◽  
Sediment Surface ◽  
Mercury Methylation ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Decreasing Ph ◽  
Mercury Production

Specific rates of mercury methylation and demethylation were determined for water and surficial sediment samples taken from several lakes located in the Experimental Lakes Area, northwestern Ontario. Specific rates of mercury methylation were found to increase with decreasing pH in epilimnetic water samples in which pH was adjusted prior to incubation and in epilimnetic water samples taken from lakes of different pH. Reduction of pH also increased methyl mercury production at the sediment surface. Both increases and decreases in pH reduced specific rates of mercury demethylation. However, these changes were smaller than for methylation. Proportionally, specific rates of methylation increased faster than increasing concentrations of Hg2+, while specific rates of mercury demethylation increased linearly with increasing concentrations of methyl mercury. Overall, this study predicts that the net rate of methyl mercury production in the water column and at the sediment–water surface will increase as a result of lake acidification, and this may at least partially explain why the mercury concentration of fish appears to increase during lake acidification.

Fates of Metal Radiotracers Added to a Whole Lake: Sediment–Water Interactions

1980 ◽  
Vol 37 (3) ◽  
pp. 378-386 ◽  
Author(s):  
R. H. Hesslein ◽  
W. S. Broecker ◽  
D. W. Schindler
Keyword(s):  
Water Column ◽  
Environmental Fate ◽  
Particulate Material ◽  
Experimental Lakes Area ◽  
Suspended Particulates ◽  
Northwestern Ontario ◽  
Suspended Particulate ◽  
Suspended Particulate Material ◽  
Deep Sediments ◽  
Dissolved Form

A whole-lake radiotracer experiment with the isotopes Se-75, Hg-203, Cs-134, Fe-59, Co-60 was carried out in Lake 224 of the Experimental Lakes Area, northwestern Ontario. The results of the analyses of isotopes in the water column show an exponential decrease in concentration with time. The rate of loss from the water column does not show dependence on the affinity of the isotope for suspended particulate material. This affinity ranged from 98% for Fe-59 to < 1% for Cs-134 over the first 65 d. The major sink for isotopes lost from the water column is the sediments. Ratios of isotopes in the sediments show that those isotopes associated with suspended particulates more easily reach deep sediments than those in dissolved form which are restricted by the thermocline to adsorption to epilimnion sediments.Key words: Experimental Lakes Area, metal and radioisotope budgets, environmental fate of radionuclides

Chemical Factors Involved in the Control of Phytoplankton Production in the Experimental Lakes Area, Northwestern Ontario

1971 ◽  
Vol 28 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Mitsuru Sakamoto
Keyword(s):  
Inorganic Carbon ◽  
Phytoplankton Production ◽  
Carbon Uptake ◽  
Short Term ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Photosynthetic Carbon ◽  
General Order ◽  
Chemical Factors

In short-term experiments (6 hr–3 days) the general order of decreasing importance of nutrients added individually to samples of lake water and contained phytoplankton was inorganic carbon, Fe, P, and N. The comparable order for long-term experiments (8–20 days) was P, Fe, N; or P, N, Fe. No relation was found between concentrations of chlorophyll and inorganic carbon in the lakes. The addition of iron and trace elements in chelated form and chelators (HEDTA, NTA) alone, increased photosynthetic carbon uptake. The deficiency of iron was mostly due to a lack of iron in a readily assimilable form.

Response of Radioactive Trace Metals to Acid–Base Titrations in Controlled Experimental Ecosystems: Evaluation of Transport Parameters for Application to Whole-Lake Radiotracer Experiments

1986 ◽  
Vol 43 (1) ◽  
pp. 60-77 ◽  
Author(s):  
Peter H. Santschi ◽  
Urs P. Nyffeler ◽  
Robert F. Anderson ◽  
Sherry L. Schiff ◽  
Patricia O'hara ◽  
...  
Keyword(s):  
Trace Metals ◽  
Water Column ◽  
Metal Removal ◽  
Transport Model ◽  
Transport Parameters ◽  
Removal Rates ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Boundary Film ◽  
Experimental Ecosystems

Radiotracer experiments were carried out in 20 enclosures located in two lakes at the Experimental Lakes Area (ELA), northwestern Ontario, to study pathways of trace metal removal from the water column of shallow lakes. Two removal mechanisms were characterized: (1) sorption to and subsequent transport with falling particles and (2) direct adsorption to surface sediments. Our approach was to measure independently the kinetics of radiotracer sorption, fluxes and concentrations for particles, particle settling velocities, and the "equivalent stagnant boundary film." Our radiotracer results enabled us to test the sensitivity of the tracer removal rates on these rate-determining processes using a numerical transport model. Acid titrations of whole ecosystems revealed that some trace metals (e.g. Mn, Co, and Zn) can diffuse back to the water column as the pH is lowered from 6.5 to 4.8 after 18 d, while others remain tightly bound (e.g. Sn, Fe, Se, Cr, Ag, and Hg isotopes). Subsequent CaCO3 additions to bring back the pH to its original value restored the initial removal conditions for acid-sensitive radiotracers, indicating that the pH sensitivity is reversible. Transport parameters for particle-related pathways or diffusive pathways across the sediment–water interface obtained from our enclosure experiments were used to predict the removal rates of "particle-reactive" 60Co and the "diffusive" pathway tracer 134Cs observed in earlier experiments where radiotracers were added to whole lakes or to larger enclosures.

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.

Subglacial brine flow and wind-induced internal waves in Lake Bonney, Antarctica

2020 ◽  
Vol 32 (3) ◽  
pp. 223-237
Author(s):  
Jade P. Lawrence ◽  
Peter T. Doran ◽  
Luke A. Winslow ◽  
John C. Priscu
Keyword(s):  
Water Column ◽  
Internal Waves ◽  
Open Water ◽  
Surface Discharge ◽  
Katabatic Wind ◽  
Neutral Buoyancy ◽  
Cold Temperatures ◽  
Glacier Terminus ◽  
Wind Events ◽  
Taylor Glacier

AbstractBrine beneath Taylor Glacier has been proposed to enter the proglacial west lobe of Lake Bonney (WLB) as well as from Blood Falls, a surface discharge point at the Taylor Glacier terminus. The brine strongly influences the geochemistry of the water column of WLB. Year-round measurements from this study are the first to definitively identify brine intrusions from a subglacial entry point into WLB. Furthermore, we excluded input from Blood Falls by focusing on winter dynamics when the absence of an open water moat prevents surface brine entry. Due to the extremely high salinities below the chemocline in WLB, density stratification is dominated by salinity, and temperature can be used as a passive tracer. Cold brine intrusions enter WLB at the glacier face and intrude into the water column at the depth of neutral buoyancy, where they can be identified by anomalously cold temperatures at that depth. High-resolution measurements also reveal under-ice internal waves associated with katabatic wind events, a novel finding that challenges long-held assumptions about the stability of the WLB water column.

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