Equatorial Africa, with an Account of the Race of Pigmies

1870 ◽  
Vol 2 (2) ◽  
pp. 99 ◽  
Author(s):  
Paul B. Du Chaillu
Keyword(s):  
Equatorial Africa

INVESTIGATING PALEOENVIRONMENTAL CHANGE DURING THE HOLOCENE USING A STALAGMITE FROM MATUPI CAVE, EQUATORIAL AFRICA

2019 ◽  
Author(s):  
Laura A. Dupont ◽  
◽  
L. Bruce Railsback ◽  
L. Bruce Railsback ◽  
George A. Brook ◽  
...  
Keyword(s):  
The Holocene ◽  
Paleoenvironmental Change ◽  
Equatorial Africa

scholarly journals Sorption and Desorption of Vanadate, Arsenate and Chromate by Two Volcanic Soils of Equatorial Africa

Soil Systems ◽  
2021 ◽  
Vol 5 (2) ◽  
pp. 22
Author(s):  
Sara Gonzalez-Rodriguez ◽  
Maria Luisa Fernandez-Marcos
Keyword(s):  
Laboratory Experiments ◽  
Sorption Isotherms ◽  
Soil Samples ◽  
Mineral Surfaces ◽  
Volcanic Soils ◽  
Iron Species ◽  
Freundlich Model ◽  
Equatorial Africa ◽  
Relevant Role ◽  
Icp Mass Spectrometry

Sorption of oxyanions by soils and mineral surfaces is of interest due to their role as nutrients or pollutants. Volcanic soils are variable charge soils, rich in active forms of aluminum and iron, and capable of sorbing anions. Sorption and desorption of vanadate, arsenate, and chromate by two African andosols was studied in laboratory experiments. Sorption isotherms were determined by equilibrating at 293 K soil samples with oxyanion solutions of concentrations between 0 and 100 mg L−1 V, As, or Cr, equivalent to 0−2.0 mmol V L−1, 0−1.3 mmol As L−1, and 0−1.9 mmol Cr L−1, in NaNO3; V, As, or Cr were determined by ICP-mass spectrometry in the equilibrium solution. After sorption, the soil samples were equilibrated with 0.02 M NaNO3 to study desorption. The isotherms were adjusted to mathematical models. After desorption with NaNO3, desorption experiments were carried out with a 1 mM phosphate. The sorption of vanadate and arsenate was greater than 90% of the amount added, while the chromate sorption was much lower (19–97%). The sorption by the Silandic Andosol is attributed to non-crystalline Fe and Al, while in the Vitric Andosol, crystalline iron species play a relevant role. The V and Cr sorption isotherms fitted to the Freundlich model, while the As sorption isotherms conformed to the Temkin model. For the highest concentrations of oxyanions in the equilibrating solution, the sorbed concentrations were 37–38 mmol V kg−1, 25 mmol As kg−1, and 7.2–8.8 mmol Cr kg−1. The desorption was low for V and As and high for Cr. The comparison of the sorption and desorption isotherms reveals a pronounced hysteresis for V in both andosols and for Cr in the Silandic Andosol. Phosphate induced almost no V desorption, moderate As desorption, and considerable Cr desorption.

scholarly journals The mandrill in Gabon's rain forest—ecology, distribution and status

Oryx ◽  
1988 ◽  
Vol 22 (4) ◽  
pp. 218-228 ◽  
Author(s):  
Michael J. S. Harrison
Keyword(s):  
Rain Forest ◽  
Forest Ecology ◽  
Human Pressure ◽  
Forest Habitat ◽  
Hunting Pressure ◽  
Mandrillus Sphinx ◽  
Conservation Measures ◽  
Equatorial Africa ◽  
In The Wild

Little is known about the mandrill Mandrillus sphinx in the wild. It is an elusive primate and thus difficult to study in its rain-forest habitat in equatorial Africa. As human pressure on its habitat grows it has become increasingly urgent to discover more about the species so that appropriate conservation measures can be planned. The author made a 15-month study of the mandrill in Gabon and discovered that it was not as widely distributed as had been believed. Although it is threatened by hunting pressure and habitat disruption, populations still remain and five reserves protect some of these.

Saving the gorillas (Gorilla g. gorilla) and chimpanzees (Pan t. troglodytes) of the Congo Basin

2001 ◽  
Vol 13 (8) ◽  
pp. 469 ◽  
Author(s):  
Caroline E. G. Tutin
Keyword(s):  
West Africa ◽  
Social Behaviour ◽  
Congo Basin ◽  
Tropical Rainforests ◽  
Forest Fragments ◽  
Vulnerable Species ◽  
Wild Populations ◽  
Non Invasive ◽  
Equatorial Africa ◽  
Invasive Techniques

The forests of the Congo Basin in equatorial Africa are home to significant populations of gorillas and chimpanzees. However, numbers are declining owing to hunting and to alteration of their habitat. Gorillas and chimpanzees are particularly vulnerable for biological reasons: slow reproduction, prolonged developmental periods and complex social behaviour. In addition, their capacity to recover from disturbance is limited and the reinforcement of wild populations with captive-born individuals is rarely an option. Compared with the critically endangered mountain gorillas and the beleaguered chimpanzees in forest fragments in West Africa, there are some reasons for optimism about the future of the Congo Basin apes: levels of threat remain relatively low; and conservation of tropical rainforests has become a priority of the international community. At the same time, knowledge of the ecological needs of wild apes has increased and non-invasive techniques now exist to monitor population health. Sadly, no animals remain truly ‘wild’, as their survival depends to a greater or lesser extent on management. Protected areas and laws that forbid hunting of vulnerable species are classic tools of management, but broader landscape visions are now emerging that may allow the Congo Basin to avoid the fragile scenario of larger animals persisting only in ‘island’ parks.

scholarly journals On the Relationship between Low Latitude Scintillation Onset and Sunset Terminator over Africa

2021 ◽  
Vol 13 (11) ◽  
pp. 2087
Author(s):  
Mogese Wassaie Mersha ◽  
Elias Lewi ◽  
Norbert Jakowski ◽  
Volker Wilken ◽  
Jens Berdermann ◽  
...  
Keyword(s):  
Moving Boundary ◽  
Occurrence Rate ◽  
Scintillation Index ◽  
Small Scale ◽  
Bahir Dar ◽  
Remarkable Change ◽  
Equatorial Africa ◽  
Night Side ◽  
Solar Terminator ◽  
First Time

The solar terminator is a moving boundary between day-side and night-side regions on the Earth, which is a substantial source of perturbations in the ionosphere. In the vicinity of the solar terminator, essential parameters like S4 index measurements are widely analyzed in order to monitor and predict perturbations in the ionosphere. The utilization of the scintillation index S4 is a well-accepted approach to describe the amplitude/intensity fluctuation of a received signal, predominantly caused by small-scale irregularities of the ionospheric plasma. We report on the longitudinal daily and seasonal occurrence of GNSS signal scintillations, using the data derived from the GNSS stations in Bahir Dar, Ethiopia, Lomé, Togo and Dakar, Senegal. The observed seasonal climatology of GNSS signal scintillations in equatorial Africa is adequately explained by the alignment of the solar terminator and local geomagnetic declination line. It should be pointed out that the strongest scintillations are most frequently observed during the time when the solar terminator is best aligned with the geomagnetic declination line. At all three stations, the comparison of computational and observational results indicated that the scintillation activity culminated around equinoxes in the years 2014, 2015 and 2016. Comparatively, the western equatorial Africa sector has the most intense, longest-lasting, and highest scintillation occurrence rate in equinoctial seasons in all three years. For the first time, we show that the seasonal variation of the scintillation peaks changes systematically from west to east at equatorial GNSS stations over Africa. A detailed analysis of the solar day–night terminator azimuth at ionospheric heights including the time equation shows that the scintillation intensity has a maximum if the azimuth of the terminator coincides with the declination line of the geomagnetic field. Due to the remarkable change of the declination by about 10° at the considered GNSS stations, the distance between scintillation peaks increases by 46 days when moving westward from the Bahir Dar to the Dakar GNSS station. The observations agree quite well with the computational results, thus confirming Tsunoda’s theory.

scholarly journals New Rainfall Datasets for the Congo Basin and Surrounding Regions

2018 ◽  
Vol 19 (8) ◽  
pp. 1379-1396 ◽  
Author(s):  
S. E. Nicholson ◽  
D. Klotter ◽  
A. K. Dezfuli ◽  
L. Zhou
Keyword(s):  
Congo Basin ◽  
Annual Rainfall ◽  
Reconstruction Method ◽  
Validation Period ◽  
Grid Data ◽  
Statistical Reconstruction ◽  
Equatorial Africa ◽  
Spatial Reconstruction ◽  
Gauge Data ◽  
Dense Coverage

Abstract This paper describes three new rainfall datasets that have been developed for equatorial Africa. The development relies on acquisition of recent gauge data from the relevant countries and statistical methods to fill in gaps in coverage. Two of the three datasets are gridded with spatial resolutions of 2.5° and 5.0°, and the third is regionally aggregated and based purely on gauge data. The work is based on a total of 1826 gauge records in the analysis sector, of which only several hundred operate in recent years. The gridded datasets were produced and validated by using a period of dense coverage (1947–72) to “calibrate” a spatial reconstruction method, which is then utilized to grid data for the remaining years. The period 1973–2010 served as a validation period. The validation was carried out by comparing the gridded values with values obtained by simple averaging of station data in grid boxes with an adequate number of stations. This exercise clearly showed that the statistical reconstruction approach based on principal components produced far superior results than those from the more commonly used kriging. The gridded datasets cover each month of the year, six seasons, and annual rainfall, and they commence in 1921 and extend through 2014. In contrast, the gauge-only regional dataset covers varied time periods, depending on the geographical region in question. Records for several regions cover nearly all of the twentieth century and most extend to 2014.

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