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.

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.

Progress report on 21-cm observations at low latitude between longitudes (l 11) 0° and 66°

1967 ◽  
Vol 31 ◽  
pp. 177-179
Author(s):  
W. W. Shane
Keyword(s):  
Preliminary Report ◽  
Progress Report ◽  
Galactic Centre ◽  
Low Latitude ◽  
The Third ◽  
Introductory Lecture ◽  
Centre Region

In the course of several 21-cm observing programmes being carried out by the Leiden Observatory with the 25-meter telescope at Dwingeloo, a fairly complete, though inhomogeneous, survey of the regionl11= 0° to 66° at low galactic latitudes is becoming available. The essential data on this survey are presented in Table 1. Oort (1967) has given a preliminary report on the first and third investigations. The third is discussed briefly by Kerr in his introductory lecture on the galactic centre region (Paper 42). Burton (1966) has published provisional results of the fifth investigation, and I have discussed the sixth in Paper 19. All of the observations listed in the table have been completed, but we plan to extend investigation 3 to a much finer grid of positions.

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:

Sign in / Sign up

Export Citation Format

Share Document