An In Situ Study of Cadmium and Mercury Stress in the Plankton Community of Lake 382, Experimental Lakes Area, Northwestern Ontario

1981 ◽  
Vol 38 (10) ◽  
pp. 1209-1214 ◽  
Author(s):  
J. S. Marshall ◽  
J. I. Parker ◽  
D. L. Mellinger ◽  
S. G. Lawrence
Keyword(s):  
Inorganic Mercury ◽  
Zooplankton Community ◽  
Plankton Community ◽  
Crustacean Zooplankton ◽  
Experimental Lakes Area ◽  
In Situ Experiments ◽  
Toxic Concentrations ◽  
Shield Lakes ◽  
Plankton Communities

Four in situ experiments with small-volume (28-L) enclosures were conducted in Experimental Lakes Area Lake 382 to assess the effects of inorganic mercury and cadmium on the plankton community. Additions of 0.9 × 10−8 mol Cd/L caused significant reductions of crustacean zooplankton density, zooplankton community similarity, zooplankton species diversity, and dissolved oxygen concentration over 3-wk periods. Additions of 1.0 × 10−8 mol Hg/L caused reductions similar to those of 0.9 × 10−8 mol Cd/L. Phytoplankton primary productivity was reduced by additions of 2.0 × 10−8 mol Hg/L but not by 1.0 × 10−8 mol Hg/L. On a molar concentration basis, the toxicities of inorganic mercury and cadmium were quite similar. Significant changes in lake plankton communities may occur at molar concentrations above 0.2 × 10−8 mol/L. Potentially toxic concentrations of cadmium may occur in many contaminated lakes, but toxic concentrations of mercury probably occur in few lakes.Key words: Precambrian Shield lakes, plankton communities, phytoplankton, zooplankton, cadmium, mercury toxicity

Dynamics of Cadmium-Stressed Plankton Communities

1980 ◽  
Vol 37 (3) ◽  
pp. 403-414 ◽  
Author(s):  
J. S. Marshall ◽  
D. L. Mellinger
Keyword(s):  
Dissolved Oxygen ◽  
Lake Michigan ◽  
Zooplankton Community ◽  
Cadmium Stress ◽  
Crustacean Zooplankton ◽  
Functional Responses ◽  
Experimental Lakes Area ◽  
Individual Values ◽  
Zooplankton Density ◽  
Plankton Communities

Structural and functional responses of plankton communities to cadmium stress were studied during 1977 in Lake Michigan using small-volume (8 L) completely sealed enclosures, and in Canada's Experimental Lakes Area (ELA) Lake 223 using large-volume (1.5 × 105 L) open-surface enclosures. In Lake Michigan, reductions of the average abundance of micro-crustaceans by cadmium were significantly greater in "light" or shallow epilimnetic incubations than they were in "dark" or deep epilimnetic incubations. Measurements of dissolved oxygen indicated that this interaction with light (depth) was an indirect effect due to a reduction of photosynthesis and primary production. Zooplankton density and species diversity were not significantly affected within 21 d by cadmium concentrations [Formula: see text] and [Formula: see text] Cd/L, respectively, whereas final dissolved oxygen concentration and percentage similarity (PS) of the crustacean zooplankton community were significantly reduced by [Formula: see text] Cd/L. In the ELA Lake 223 experiment, the reducing effect of cadmium on zooplankton density increased up to 31 d after Cd enrichment and then decreased, probably due to decreasing Cd concentrations in the water. Values of PS on day 24 for the ELA enclosures enriched with 1 and 3 μg Cd/L were within the 95% confidence limits for individual values predicted from a regression of PS on cadmium for the 21-d Lake Michigan experiments.Key words: plankton communities, zooplankton, phytoplankton, cadmium stress, Lake Michigan, Canadian Shield lakes

Calibration of the zooplankton community size spectrum as an indicator of change in Canadian Shield lakes

2019 ◽  
Vol 76 (12) ◽  
pp. 2268-2287
Author(s):  
Lauren Emily Barth ◽  
Brian John Shuter ◽  
William Gary Sprules ◽  
Charles Kenneth Minns ◽  
James Anthony Rusak
Keyword(s):  
Zooplankton Community ◽  
Canadian Shield ◽  
Rate Of Change ◽  
Crustacean Zooplankton ◽  
Size Spectrum ◽  
Community Size ◽  
Mean Values ◽  
Sampling Protocols ◽  
Stable Characteristic ◽  
Shield Lakes

Developing the crustacean zooplankton community size spectrum into an indicator of change in lakes requires quantification of the natural variability in the size spectrum related to broad-scale seasonal, annual, and spatial factors. Characterizing seasonal patterns of variation in the size spectrum is necessary so that monitoring programs can be designed to minimize the masking effects that seasonal processes can have on detecting longer-term temporal change. We used a random effects model to measure monthly, annual, and interlake variability in the slope (i.e., relative abundance of small and large organisms) and centered height (i.e., total abundance) of the crustacean zooplankton normalized abundance size spectrum from 1981 to 2011 among eight Canadian Shield lakes. Consistent with theoretical predictions, the slope was a relatively stable characteristic of the zooplankton community compared with the height, which varied significantly among lakes. We identified a seasonal signal in height and slope and used a mixed effects model to characterize the linear rate of change from May to October; there was an overall decline in height and an overall increase in slope. Seasonal variance was greater than annual variance for both the height and the slope, suggesting that long-term monitoring of lakes and interlake comparisons using zooplankton size spectra should be based on temporally standardized sampling protocols that minimize the effects of seasonal processes. We recommend sampling the zooplankton community in midsummer because this results in size spectrum estimates close to seasonal mean values.

Bioaccumulation and Effects of Cadmium and Zinc in a Lake Michigan Plankton Community

1983 ◽  
Vol 40 (9) ◽  
pp. 1469-1479 ◽  
Author(s):  
J. S. Marshall ◽  
J. I. Parker ◽  
D. L. Mellinger ◽  
C. Lei
Keyword(s):  
Community Structure ◽  
Species Diversity ◽  
Lake Michigan ◽  
Plankton Community ◽  
Crustacean Zooplankton ◽  
Zooplankton Species ◽  
Community Similarity ◽  
Zooplankton Community Structure ◽  
Keratella Cochlearis ◽  
In Situ Experiments

We conducted four in situ experiments in the southern basin of Lake Michigan to determine the responses of the plankton community to additions of cadmium (3 μg/L) and zinc (15, 30, 60, and 90 μg/L) as well as the bioaccumulation of zinc by different species of crustacean zooplankton. Total cadmium and zinc concentrations in treated enclosures (accounting for pretreatment lakewater concentrations of ~ 20 ng Cd and ~ 1 μg Zn per litre) were calculated from measurements of 109Cd and 65Zn with known specific activities.Zinc significantly reduced zooplankton populations and several other properties of community structure and function at concentrations much lower than those previously reported to be toxic to zooplankton and well below the levels established for protection of freshwater life. Zinc additions as low as 15 μg/L significantly reduced chlorophyll a, primary productivity, dissolved oxygen, specific zooplankton populations, zooplankton species diversity, and community similarity within 2 wk. Populations of several zooplankton species were severely reduced by 15 μg/L; for example, the population of the rotifer Conochilus unicornis was reduced to less than 1% of that in controls. Secondary, indirect effects included significant increases of a few populations, including Bosmina longirostris and Keratella cochlearis, for zinc additions of 15 and 30 μg/L. Most of the populations and community properties that we measured showed somewhat different percentage reductions in response to a given zinc addition at different times, but their relative (rank) values at different times were similar. Specific zooplankton populations were more sensitive to zinc than community similarity indices, and species diversity indices were relatively insensitive. Bioaccumulation of zinc by different species of crustaceans increased with added zinc but showed few significant differences among species. The small differences among species could, nevertheless, partially account for some of the observed changes in zooplankton community structure.

Relating crustacean zooplankton community structure to residential development and land-cover disturbance near Canadian Shield lakes

2008 ◽  
Vol 65 (12) ◽  
pp. 2689-2702 ◽  
Author(s):  
Malorie Gélinas ◽  
Bernadette Pinel-Alloul
Keyword(s):  
Land Cover ◽  
Human Disturbance ◽  
Variation Partitioning ◽  
Zooplankton Community ◽  
Residential Development ◽  
Canadian Shield ◽  
Crustacean Zooplankton ◽  
Zooplankton Community Structure ◽  
Intermediate Element ◽  
Shield Lakes

We applied the land-cover cascade (LCC) concept to evaluate whether human disturbance affects crustacean zooplankton community in 13 nutrient-poor lakes of the Laurentian region along a gradient of residential development and land-cover disturbance. Zooplankton biomass responded indirectly to residential disturbances within the watershed based on path analysis. In most LCC models, total phosphorus enrichment was a strong intermediate element linking residential disturbances to increased biomass of small crustaceans ( Bosmina , Ceriodaphnia , and Diaphanosoma ) and Daphnia species ( D. g. mendotae , D. dubia , and D. ambigua ). Zooplanktivory index was also an intermediate element in LCC models of crustacean functional groups and an independent element in daphnid-based LCC models. Low zooplanktivory was associated with higher biomass of large Daphnia ( D. pulicaria and D. catawba ). However, residential disturbance and select environmental factors (phosphate enrichment, zooplanktivory index, lake depth, littoral macrophytes) explained only 42% and 57%, respectively, of among-lake variation in crustacean community and Daphnia assemblages. Variation partitioning analysis suggested that planktivory had a similar or greater influence than human disturbance and phosphate enrichment. Our study improves the knowledge of crustacean zooplankton responses to increasing residential development and land-use disturbances near Canadian Shield lakes.

An in situ and ex situ TEM study of the formation of thin cobalt silicide films by molecular beam epitaxy on the silicon (100) surface

1988 ◽  
Vol 46 ◽  
pp. 884-885
Author(s):  
D. Loretto ◽  
J. M. Gibson ◽  
S. M. Yalisove ◽  
R. T. Tung
Keyword(s):  
Molecular Beam Epitaxy ◽  
Molecular Beam ◽  
Defect Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Metal Base ◽  
In Situ Experiments ◽  
Potential Applications

The cobalt disilicide/silicon system has potential applications as a metal-base and as a permeable-base transistor. Although thin, low defect density, films of CoSi2 on Si(111) have been successfully grown, there are reasons to believe that Si(100)/CoSi2 may be better suited to the transmission of electrons at the silicon/silicide interface than Si(111)/CoSi2. A TEM study of the formation of CoSi2 on Si(100) is therefore being conducted. We have previously reported TEM observations on Si(111)/CoSi2 grown both in situ, in an ultra high vacuum (UHV) TEM and ex situ, in a conventional Molecular Beam Epitaxy system.The procedures used for the MBE growth have been described elsewhere. In situ experiments were performed in a JEOL 200CX electron microscope, extensively modified to give a vacuum of better than 10-9 T in the specimen region and the capacity to do in situ sample heating and deposition. Cobalt was deposited onto clean Si(100) samples by thermal evaporation from cobalt-coated Ta filaments.

Electron and ion irradiation-induced dissolution of mechanical twins in the intermetalic U3Si: An in situ HVEM study

1989 ◽  
Vol 47 ◽  
pp. 652-653
Author(s):  
Charles W. Allen ◽  
Robert C. Birtcher
Keyword(s):  
Elevated Temperatures ◽  
Ion Irradiation ◽  
Ion Beam ◽  
National Laboratory ◽  
Argonne National Laboratory ◽  
Heavy Ion ◽  
High Energy ◽  
Mechanical Twinning ◽  
In Situ Experiments

The uranium silicides, including U3Si, are under study as candidate low enrichment nuclear fuels. Ion beam simulations of the in-reactor behavior of such materials are performed because a similar damage structure can be produced in hours by energetic heavy ions which requires years in actual reactor tests. This contribution treats one aspect of the microstructural behavior of U3Si under high energy electron irradiation and low dose energetic heavy ion irradiation and is based on in situ experiments, performed at the HVEM-Tandem User Facility at Argonne National Laboratory. This Facility interfaces a 2 MV Tandem ion accelerator and a 0.6 MV ion implanter to a 1.2 MeV AEI high voltage electron microscope, which allows a wide variety of in situ ion beam experiments to be performed with simultaneous irradiation and electron microscopy or diffraction.At elevated temperatures, U3Si exhibits the ordered AuCu3 structure. On cooling below 1058 K, the intermetallic transforms, evidently martensitically, to a body-centered tetragonal structure (alternatively, the structure may be described as face-centered tetragonal, which would be fcc except for a 1 pet tetragonal distortion). Mechanical twinning accompanies the transformation; however, diferences between electron diffraction patterns from twinned and non-twinned martensite plates could not be distinguished.

A computer-control program for TEM in situ fatigue experiments

1989 ◽  
Vol 47 ◽  
pp. 620-621
Author(s):  
Kenneth S. Vecchio ◽  
John A. Hunt
Keyword(s):  
Slow Crack Growth ◽  
Computer Control ◽  
Control Program ◽  
Video Tape ◽  
Computer Control System ◽  
Transmission Electron ◽  
In Situ Experiments ◽  
Tremendous Amount ◽  
And Control

In-situ experiments conducted within a transmission electron microscope provide the operator a unique opportunity to directly observe microstructural phenomena, such as phase transformations and dislocation-precipitate interactions, “as they happen”. However, in-situ experiments usually require a tremendous amount of experimental preparation beforehand, as well as, during the actual experiment. In most cases the researcher must operate and control several pieces of equipment simultaneously. For example, in in-situ deformation experiments, the researcher may have to not only operate the TEM, but also control the straining holder and possibly some recording system such as a video tape machine. When it comes to in-situ fatigue deformation, the experiments became even more complicated with having to control numerous loading cycles while following the slow crack growth. In this paper we will describe a new method for conducting in-situ fatigue experiments using a camputer-controlled tensile straining holder.The tensile straining holder used with computer-control system was manufactured by Philips for the Philips 300 series microscopes. It was necessary to modify the specimen stage area of this holder to work in the Philips 400 series microscopes because the distance between the optic axis and holder airlock is different than in the Philips 300 series microscopes. However, the program and interfacing can easily be modified to work with any goniometer type straining holder which uses a penrmanent magnet motor.

Coliform transport in a pristine reservoir: modeling and field studies

1998 ◽  
Vol 37 (2) ◽  
pp. 137-144 ◽  
Author(s):  
Elisa Garvey ◽  
John E. Tobiason ◽  
Michael Hayes ◽  
Evelyn Wolfram ◽  
David A. Reckhow ◽  
...  
Keyword(s):  
Model Development ◽  
Fate And Transport ◽  
Field Studies ◽  
Meteorological Conditions ◽  
Reservoir Modeling ◽  
Vertical Circulation ◽  
Quality Model ◽  
Circulation Patterns ◽  
In Situ Experiments

This paper reports on field studies and model development aimed at understanding coliform fate and transport in the Quabbin Reservoir, an oligotrophic drinking water supply reservoir. An investigation of reservoir currents suggested the importance of wind driven phenomena, and that both lateral and vertical circulation patterns exist. In-situ experiments of coliform decay suggested dependence on light intensity and yielded an appropriate decay coefficient to be used in CE-QUAL-W2, a two-dimensional hydrodynamic and water quality model. Modeling confirmed the sensitivity of reservoir outlet concentration to vertical variability within the reservoir, meteorological conditions, and location of coliform source.

scholarly journals Upscaling THM modeling from small-scale to full-scale in-situ experiments in the Callovo-Oxfordian claystone

2021 ◽  
Vol 144 ◽  
pp. 104582
Author(s):  
D.M. Seyedi ◽  
C. Plúa ◽  
M. Vitel ◽  
G. Armand ◽  
J. Rutqvist ◽  
...  
Keyword(s):  
Full Scale ◽  
Small Scale ◽  
In Situ Experiments
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