Temperature and light: The determining factors in maximum depth distribution of aquatic macrophytes in Ontario, Canada

Hydrobiologia ◽  
1986 ◽  
Vol 133 (1) ◽  
pp. 73-77 ◽  
Author(s):  
H. M. Dale
Keyword(s):  
Aquatic Macrophytes ◽  
Depth Distribution ◽  
Maximum Depth ◽  
Determining Factors

Latitudinal influences on the Depths of Maximum Colonization and Maximum Biomass of Submerged Angiosperms in Lakes

1987 ◽  
Vol 44 (10) ◽  
pp. 1759-1764 ◽  
Author(s):  
Carlos M. Duarte ◽  
Jacob Kalff
Keyword(s):  
Depth Distribution ◽  
Maximum Depth ◽  
Water Transparency ◽  
Submerged Plants ◽  
Low Latitude ◽  
Maximum Biomass ◽  
Submerged Angiosperms ◽  
Macrophyte Cover

Both water transparency and lake latitude influence the depths of maximum biomass (Zb) and maximum depth of colonization (Zc) of submerged plants. The differences in the depth distribution of plants in lakes differing in water transparency become more pronounced as latitude decreases. Changes in transparency in low-latitude lakes should result in greater changes in macrophyte cover than similar changes in lakes at higher latitudes. The maximum depth of colonization appears to be largely a function of water transparency, whereas the depth of maximum biomass is best related to latitude. Relationships developed here allow better predictions of Zc and Zb for individual lakes than were possible before.

scholarly journals Hydrologic cycle and dynamics of aquatic macrophytes in two intermittent rivers of the semi-arid region of Brazil

2006 ◽  
Vol 66 (2b) ◽  
pp. 575-585 ◽  
Author(s):  
F. Pedro ◽  
L. Maltchik ◽  
I. Bianchini Jr.
Keyword(s):  
Arid Region ◽  
Aquatic Macrophytes ◽  
Aquatic Macrophyte ◽  
Aquatic Communities ◽  
Variable Intensity ◽  
Run Off ◽  
Intermittent Rivers ◽  
Determining Factors ◽  
Semi Arid Region ◽  
Semi Arid

The dynamics of aquatic macrophytes in intermittent rivers is generally related to the characteristics of the resistance and resilience of plants to hydrologic disturbances of flood and drought. In the semi-arid region of Brazil, intermittent rivers and streams are affected by disturbances with variable intensity, frequency, and duration throughout their hydrologic cycles. The aim of the present study is to determine the occurrence and variation of biomass of aquatic macrophyte species in two intermittent rivers of distinct hydrologic regimes. Their dynamics were determined with respect to resistance and resilience responses of macrophytes to flood and drought events by estimating the variation of biomass and productivity throughout two hydrologic cycles. Twenty-one visits were undertaken in the rewetting, drying, and drought phases in a permanent puddle in the Avelós stream and two temporary puddles in the Taperoá river, state of Paraíba, Northeast Brazil. The sampling was carried out by using the square method. Floods of different magnitudes occurred during the present study in the river and in the stream. The results showed that floods and droughts are determining factors in the occurrence of macrophytes and in the structure of their aquatic communities. The species richness of the aquatic macrophyte communities was lower in the puddles of the river and stream subject to flood events, when compared to areas where the run-off water is retained. At the beginning of the recolonization process, the intensity of the floods was decisive in the productivity and biomass of the aquatic macrophytes in the Taperoá river and the Avelós stream. In intermediate levels of disturbance, the largest values of productivity and biomass and the shortest time for starting the recolonization process occurred.

On maximum depth classifiers: depth distribution approach

2017 ◽  
Vol 45 (6) ◽  
pp. 1106-1117 ◽  
Author(s):  
Olusola Samuel Makinde ◽  
Olusoga Akin Fasoranbaku
Keyword(s):  
Depth Distribution ◽  
Maximum Depth

Depth Distribution and Biomass of Submersed Aquatic Macrophyte Communities in Relation to Secchi Depth

1985 ◽  
Vol 42 (4) ◽  
pp. 701-709 ◽  
Author(s):  
Patricia A. Chambers ◽  
Jacob Kaiff
Keyword(s):  
Regression Models ◽  
Depth Distribution ◽  
Aquatic Macrophyte ◽  
Secchi Depth ◽  
Environmental Parameters ◽  
Growing Season ◽  
Original Data ◽  
Maximum Depth ◽  
Macrophyte Communities ◽  
Surface Changes

Using original data from eight lakes in southern Quebec and literature values from other fakes throughout the world, regression models were developed that allow prediction of the maximum depth of macrophyte colonization (zc) for angiosperms ((zc)0.5 = 1.33 log (D) + 1.40), bryophytes (zc)−0.5 = −0.48 log (D) + 0.81), and charophytes (log (zc) = 0.87 log (D) + 0.31) and the depth of maximum angiosperm biomass (zb)(zb0.5 = 0.54 log (D) + 1.15) from mean summer Secchi depth (D). Irradiance over the growing season at the maximum depth of colonization was about 1800 J/cm2 (1 cal/cm2 = 0.239 J/cm2) for angiosperms and bryophytes and 1200 J/cm2 for charophytes. These values represent, on average, 21 and 11% of the photo-synthetically available radiation incident on the water surface. Changes in maximum angiosperm biomass were, however, not correlated with Secchi depth. This suggests that while the depth distribution of aquatic macrophyte communities is primarily controlled by irradiance, environmental parameters other than irradiance and nutrients are also important in determining maximum angiosperm biomass in individual lakes.

Applications of SIMS to electronic materials and devices

1992 ◽  
Vol 50 (2) ◽  
pp. 1682-1683
Author(s):  
S.F. Corcoran
Keyword(s):  
Depth Distribution ◽  
Secondary Ion Mass Spectrometry ◽  
Semiconductor Device ◽  
Electronic Materials ◽  
Profile Analysis ◽  
Semiconductor Industry ◽  
Small Diameter ◽  
Depth Resolution ◽  
Detection Sensitivity

Over the past decade secondary ion mass spectrometry (SIMS) has played an increasingly important role in the characterization of electronic materials and devices. The ability of SIMS to provide part per million detection sensitivity for most elements while maintaining excellent depth resolution has made this technique indispensable in the semiconductor industry. Today SIMS is used extensively in the characterization of dopant profiles, thin film analysis, and trace analysis in bulk materials. The SIMS technique also lends itself to 2-D and 3-D imaging via either the use of stigmatic ion optics or small diameter primary beams.By far the most common application of SIMS is the determination of the depth distribution of dopants (B, As, P) intentionally introduced into semiconductor materials via ion implantation or epitaxial growth. Such measurements are critical since the dopant concentration and depth distribution can seriously affect the performance of a semiconductor device. In a typical depth profile analysis, keV ion sputtering is used to remove successive layers the sample.

Fluorescence effects in quantitative microprobe analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 188-189
Author(s):  
S.J.B. Reed
Keyword(s):  
Microprobe Analysis ◽  
Depth Distribution ◽  
Exciting Radiation ◽  
Primary Radiation ◽  
List Type ◽  
Type Number ◽  
Computing Power ◽  
X Ray ◽  
Fluorescent Radiation

Characteristic fluorescenceThe theory of characteristic fluorescence corrections was first developed by Castaing. The same approach, with an improved expression for the relative primary x-ray intensities of the exciting and excited elements, was used by Reed, who also introduced some simplifications, which may be summarized as follows (with reference to K-K fluorescence, i.e. K radiation of element ‘B’ exciting K radiation of ‘A’):1.The exciting radiation is assumed to be monochromatic, consisting of the Kα line only (neglecting the Kβ line).2.Various parameters are lumped together in a single tabulated function J(A), which is assumed to be independent of B.3.For calculating the absorption of the emerging fluorescent radiation, the depth distribution of the primary radiation B is represented by a simple exponential.These approximations may no longer be justifiable given the much greater computing power now available. For example, the contribution of the Kβ line can easily be calculated separately.

A New Numerical Model for Electron-Probe Analysis at High Depth Resolution

1996 ◽  
Vol 54 ◽  
pp. 490-491
Author(s):  
P.-F. Staub ◽  
C. Bonnelle ◽  
F. Vergand ◽  
P. Jonnard
Keyword(s):  
Electron Probe ◽  
Surface Segregation ◽  
Depth Distribution ◽  
Computing Time ◽  
Depth Resolution ◽  
Physical Parameters ◽  
Electron Probe Analysis ◽  
Interface Phases ◽  
Excitation Conditions ◽  
High Depth

Characterizing dimensionally and chemically nanometric structures such as surface segregation or interface phases can be performed efficiently using electron probe (EP) techniques at very low excitation conditions, i.e. using small incident energies (0.5<E0<5 keV) and low incident overvoltages (1<U0<1.7). In such extreme conditions, classical analytical EP models are generally pushed to their validity limits in terms of accuracy and physical consistency, and Monte-Carlo simulations are not convenient solutions as routine tools, because of their cost in computing time. In this context, we have developed an intermediate procedure, called IntriX, in which the ionization depth distributions Φ(ρz) are numerically reconstructed by integration of basic macroscopic physical parameters describing the electron beam/matter interaction, all of them being available under pre-established analytical forms. IntriX’s procedure consists in dividing the ionization depth distribution into three separate contributions:

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