scholarly journals South America: An Outline of Its Physical Geography: Discussion

1901 ◽  
Vol 17 (4) ◽  
pp. 407
Author(s):  
E. J. Payne ◽  
Senor Aramayo ◽  
Howard Saunders ◽  
Colonel Church
Keyword(s):  
South America ◽  
Physical Geography

Future Environments of South America

2007 ◽  
Author(s):  
Thomas T. Veblen ◽  
Kenneth R. Young
Keyword(s):  
South America ◽  
Environmental Change ◽  
Environmental Changes ◽  
Human Impacts ◽  
Southern Oscillation ◽  
Physical Geography ◽  
Tierra Del Fuego ◽  
South American ◽  
Policy Options ◽  
Natural Processes

An important goal of this book has been to provide a comprehensive understanding of the physical geography and landscape origins of South America as important background to assessing the probabilities and consequences of future environmental changes. Such background is essential to informed discussions of environmental management and the development of policy options designed to prepare local, national, and international societies for future changes. A unifying theme of this book has been the elucidation of how natural processes and human activities have interacted in the distant and recent past to create the modern landscapes of the continent. This retrospective appreciation of how the current landscapes have been shaped by nature and humans will guide our discussion of possible future trajectories of South American environments. There is abundant evidence from all regions of South America, from Tierra del Fuego to the Isthmus of Panama, that environmental change, not stasis, has been the norm. Given that fact, the history, timing, and recurrence intervals of this dynamism are all crucial pieces of information. The antiquity and widespread distribution of changes associated with the indigenous population are now well established. Rates and intensities of changes related to indigenous activities varied widely, but even in regions formerly believed to have experienced little or no pre-European impacts we now recognize the effects of early humans on features such as soils and vegetation. Colonization by Europeans mainly during the sixteenth century modified or in some cases replaced indigenous land-use practices and initiated changes that have continued to the present. Complementing these broad historical treatments of human impacts, other chapters have examined in detail the environmental impacts of agriculture (chapter 18) and urbanism (chapter 20), and the disruptions associated with El Niño–Southern Oscillation events. The goal of this final synthesis is to identify the major drivers of change and to discuss briefly their likely impacts on South American environments and resources in the near and medium-term future. Our intent is not to make or defend predictions, but rather to identify broad causes and specific drivers of environmental change to inform discussions of policy options for mitigating undesirable changes and to facilitate potential societal adaptations to them.

The Physical Geography of South America

2007 ◽  
Author(s):  
Thomas Veblen ◽  
Kenneth Young ◽  
Antony Orme
Keyword(s):  
South America ◽  
Amazon Basin ◽  
Physical Geography ◽  
Environmental Literature ◽  
South American ◽  
High Mountains ◽  
Natural Landscape ◽  
Modern Agriculture ◽  
Body Of Knowledge ◽  
Main Components

The Physical Geography of South America, the eighth volume in the Oxford Regional Environments series, presents an enduring statement on the physical and biogeographic conditions of this remarkable continent and their relationships to human activity. It fills a void in recent environmental literature by assembling a team of specialists from within and beyond South America in order to provide an integrated, cross-disciplinary body of knowledge about this mostly tropical continent, together with its high mountains and temperate southern cone. The authors systematically cover the main components of the South American environment - tectonism, climate, glaciation, natural landscape changes, rivers, vegetation, animals, and soils. The book then presents more specific treatments of regions with special attributes from the tropical forests of the Amazon basin to the Atacama Desert and Patagonian steppe, and from the Atlantic, Caribbean, and Pacific coasts to the high Andes. Additionally, the continents environments are given a human face by evaluating the roles played by people over time, from pre-European and European colonial impacts to the effects of modern agriculture and urbanization, and from interactions with El Niño events to prognoses for the future environments of the continent.

scholarly journals South America: An Outline of Its Physical Geography

1901 ◽  
Vol 17 (4) ◽  
pp. 333 ◽  
Author(s):  
George Earl Church
Keyword(s):  
South America ◽  
Physical Geography

Agriculture and Soil Erosion

2007 ◽  
Author(s):  
Carol P. Harden ◽  
Glenn G. Hyman
Keyword(s):  
Soil Erosion ◽  
South America ◽  
International Development ◽  
Urban Areas ◽  
Amazon Basin ◽  
Physical Geography ◽  
Natural Environments ◽  
Post Colonial ◽  
Agricultural Trends ◽  
Preferred Species

People have manipulated the natural environments of South America for agricultural purposes for several millennia. While agriculture is strongly affected by the physical attributes of a place—soil, water, climate, biota, and topography—agriculture changes a landscape’s physical and biological characteristics and processes. Agriculture may involve short- and long-term conversion of forest to cropland and pasture, modification of topography and drainage, and the introduction and propagation of exotic species. Soil erosion, much of which is caused by agriculture, is a major concern in South America. This chapter introduces the patterns of agriculture in South America and examines agricultural trends. It then reviews the causes and consequences of soil erosion at continental to local scales, providing examples from research conducted across the continent. As population grows and demand for agricultural production increases, knowledge of the physical geography of soil erosion will be even more critical for the sustainability of agriculture in South America. Agriculture is broadly defined here to encompass annual and permanent crops, tree crops, and livestock. Agricultural patterns of South America today reflect great differences in the continent’s natural environments. They also reflect the influence of international and global markets, the impacts of national policies, and the imprints of preand post-colonial settlement patterns, preferred species, and cultural preferences. The wide range of climates in South America allows a great variety of temperate and tropical fruits, vegetables, and grains to flourish. Historically, the diverse agricultural capabilities of different parts of the continent have been fundamental influences in the development of pre- and post-colonial human habitation and economic patterns (U.S. Agency for International Development, 1993; see chapters 16 and 17). At the continental scale, agriculture occurs across almost all regions of South America. It is notably absent only in the Gran Chaco, rugged portions of the high Andes, and desert landscapes along the Pacific coast of northern Chile and southern Perú. In practice, there is little cropland in sparsely populated regions, especially in the Amazon basin, and in densely populated urban areas, even where the lands and climates of those places are capable of supporting agriculture.

Deposition  of plutonium isotopes in glacial environments in the Northern and Southern Hemispheres

2021 ◽  
Author(s):  
Edyta Łokas ◽  
Giovanni Baccolo Baccolo ◽  
Caroline Clason ◽  
Przemysław Wachniew ◽  
Nozomu Takeuchi ◽  
...  
Keyword(s):  
South America ◽  
Heterotrophic Bacteria ◽  
Physical Geography ◽  
Radioactive Fallout ◽  
Trophic Chain ◽  
European Alps ◽  
Science Center ◽  
Plutonium Isotopes ◽  
Activity Ratios ◽  
Pu Isotopes

<p>Glaciers are temporary repositories for radionuclides and other airborne contaminants (eg. heavy metals). Retreat of glaciers results in the release of these contaminants to downstream ecosystems where they can be accumulated by biota, with further consequences along the trophic chain. Fallout radionuclides, and especially Pu released from nuclear weapons testing and nuclear accidents, concentrates on glacier surfaces in cryoconite granules. These aggregates of mineral and organic components are associated with biological consortia composed of archaea, algae, cyanobacteria, fungi and heterotrophic bacteria (Cook et al., 2016). Cryoconite is also responsible for local decrease ice albedo and is responsible for formation of water-filled holes. Contaminants are effectively trapped in cryoconite granules for long periods (up to decades) due to the “sticky” nature of the material. Cryoconite can thus be useful in monitoring of radionuclide deposition on glaciers (Łokas et al., 2019; Giovanni et al., 2020).</p><p>Our collective research reveals widespread incidence of Pu isotopes in cryoconite across multiple sites on both hemispheres, including Svalbard, Sweden, Norway, Iceland, Greenland, British Columbia, Alaska, the European Alps, the Caucasus, Siberia, Tien Shan, Altai, South America and Antarctica. The levels of plutonium isotopes (238,239,240Pu) found in cryoconite at these sites are orders of magnitude higher than those detected in non-glaciated environments, raising important questions around the role of glaciers, and specifically cryoconite, in concentrating levels of Pu isotopes above those found in the surrounding environment. The activity ratios of 238Pu/239+240Pu show that the plutonium-related radioactivity of cryoconite from the Northern hemisphere is compatible with the worldwide signal from the global radioactive fallout (0.025) but in some samples from Svalbard higher activity ratios are associated with an additional source of pure 238Pu, pointing to an influence of the SNAP-9A satellite burn up in the atmosphere occurred in 1964. Also activity ratios from South America and Antarctica are consistent with the global radioactive fallout ratio (including SNAP 9 re-entry) in the southern hemisphere (0.14), with an exception concerning cryoconite from the Exploradores Glacier (Chilean Patagonia, ratio 0.35). There are no known nuclear test sites near this glacier which could explain this anomalous value. However, there is also no information about the atmospheric re-entry of the automatic Interplanetary Station “Mars’96” which was launched on 16 November 1996. It fell off the coast of Chile near the border with Bolivia and was not found so far. There were considerable quantities of 238Pu on board of the station, with a total activity of 174 TBq (IAEA, 2001). We hypothesize that this event could explain the anomaly observed at Exploradores Glacier, confirming the unmatched potential of cryoconite to study environmental radioactivity in glacial contexts.</p><p><strong>Acknowledgements</strong></p><p>This study was supported by the National Science Center grant no. NCN 2018/31/B/ST10/03057.</p><p><strong>References</strong></p><p>Cook et al., 2016. Progress in Physical Geography, 40(1), 66-111.</p><p>Giovanni et al., 2020. CATENA, 191, 104577.</p><p>IAEA, 2001. International Atomic Energy Agency IAEA, Vienna).</p><p>Łokas et al., 2019. The Cryosphere, 13(7), 2075-2086.</p>

Physical Geography

2009 ◽  
Author(s):  
Mary Somerville
Keyword(s):  
Physical Geography
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