IS1206_a-h_TEXT.qxd
30/07/2003
1:49 AM
biogeochemical cycle — the cycling of minerals and nutrients (organic materials) in the global ecosystem. The products from the weathering of materials and the breakdown of organic matter are cycled and recycled through the atmosphere, hydrosphere, lithosphere and biosphere to maintain the functioning of the biophysical environment. Examples include the carbon cycle, the nitrogen cycle and the phosphorus cycle (see figures 9 and 46) biological diversity — see biodiversity biological oxygen demand — a measure of the amount of dissolved oxygen in waterways such as rivers (Figure 7). Such dissolved oxygen is used by fish, microorganisms as well as in the decomposition of organic matter. There is a large BOD involved in the breakdown of fats in water, for example. Where there is a large BOD the loss of dissolved oxygen can lead to the waterway being unable to support a diverse aquatic life. In areas where BOD is low only a small variety of low, oxygen-tolerant species survive such as in the deep, cold oxygen-poor waters behind dam walls (see eutrophication) biomass — the total weight of organisms in a particular area. biome — a vegetation community occupying a large area of the Earth’s surface. Examples of biomes include tropical rainforests, grasslands, tundra and temperate forests biophysical environment — an alternative term used for the natural environment. The biophysical environment is made up of the atmosphere, lithosphere, hydrosphere and biosphere. There are many features that make up the biophysical environment. Biophysical environments include forests, deserts and oceans. Biophysical features include mountains, clouds, sand dunes, rivers and plants bioremediation — using biological techniques to overcome environmental problems; for example
Page 21
planting saltbush to address dryland salinity; to introduce a competitor to control an insect pest biosphere — that part of the biophysical environment made up of living things. The biosphere includes parts of the atmosphere, the lithosphere and the hydrosphere — because various types of life exists is these ‘spheres’ biosphere reserve — an area established with the primary aim to preserve this representative area as a major ecological resource. The concept of Biosphere Reserves was put forward by UNESCO in response to worldwide environmental degradation and the unacceptably high rate of species extinction. Australia has twelve biosphere reserves — Uluru and the Tasmanian Wilderness are also World Heritage Sites; most are national parks biota — plant and animal life located in a particular area at a particular time biotic — a term used to refer to the living parts of the biophysical environment (see abiotic and ecosystem) bituminous coal — commonly known as black coal; a higher quality coal than lignite black economy — that part of the job market where information is provided to the government for the reason of evading taxation. The Black Economy operates side by side with the legal economy but it exists because of the legal tax it avoids paying black ice — a thin sheet of frost (ice) without the usual white colour usually associated with frost. Black ice is sometimes very difficult to see while travelling on roads bloc — a group such as countries or commercial organisations that, under formal agreement, operate as one body with similar objectives. This is often seen as a group making decisions for the mutual benefit of each member of the group. There are trading blocs such as OPEC and economic blocs such as the European Union (EU)
The New Geography Dictionary
21