Geographic concentrations

The sectional name Atrorubens has replaced Divaricati of Schilling and Heiser (1981) due to priority (Anashchenko, 1974). Species in the sections Agrestes and Helianthus are annuals. The section Helianthus includes H. annuus and around 10 other species, which are confined largely to the western part of the U.S. and are diploid (2n = 34) (Heiser, 1995). The Jerusalem artichoke and around 30 other members of the section Atrorubens are perennials. They are geographically concentrated in the eastern and central part of the U.S. and include diploid, tetraploid, and hexaploid species. Jerusalem artichoke is a hexaploid species (2n = 102). 

Elevated concentrations of sulfate and nitrate associated with zones of high emission density are also found in precipitation. The geographical concentration distributions in precipitation are... 

Cities are reservoirs of POPs, just by virtue of the enormous stock of products and materials geographically concentrated in the urban technosphere. Considerably less than 1 % of the reservoir of POPs leak out of the materials and products into which they were intentionally added. Urban form, due to its simplistic architecture (relative to nature) and dismrbed hydrologic regime, promotes the mobility of the POPs that escape. The leakage of POPs to the surrounding environment is of concern with respect to human and ecosystem exposure, as explained in Chapter 8. 

Let us consider a conceptual model of the reservoirs, or stocks, and flows of a POP that leads to ecosystem and human exposure, as illustrated in Figure 8.1. We assume that the chemical is used in consumer products and building materials. Further, we assume that the greatest geographic concentration of the materials and products is in cities due to high urban population densities (Chapter 6). Over time, an increasing mass of materials... 

In contrast, mass wasting represents truly episodic inputs of particulate matter to streams, such as in the form of landslides in mountainous regions. Despite their geographic concentration in the Andean portion of the Amazon basin, they codetermine the chemical and mineralogical... 

Plants of the family Amaryllidaceae are pererrrrial or bierrrrial herbs with subterranean bulbs contairring thick, fleshy bulb scales or without a typical bulb but a rhizome as in Scadoxus and Clivia. The Amaryllidaceae are widely distributed. They are richly represented in the tropics and have pronounced centres in South Africa and to a lesser extent in Andean South America. Other groups have their centre in the Mediterranean. Groups of phylogenetically related genera often have a particular geographic concentration (i). 

The second common characteristic is that these for-profit enterprises were geographically concentrated in the United States, northwestern Europe, and Japan. These areas clearly provided the most fertile environment for commercializing the new products because they were close to sources of raw material and energy, as well as to rich sources of learning in universities and research institutes. Then, even within these regions, the activities of the proprofit enterprises clustered in a very few specific areas, a tiny sample of possible global industrial locations. 

The relationship between supply, demand, and price of the PGMs is complicated by several factors, including the geographical concentration of ore bodies in South Africa and Russia, the control of production by a limited number of companies in these regions, the impact of politics, and the impact of the world economy on demand and price. Significant new demands for PGMs can lead to price increases in the short-term and potentially in the long-term if supply capacity does not increase. 

Even the manufacturer of a full line of products who has geographically concentrated customers may find direct channels less profitable than indirect channels for some of the products and customers. For example, many pharmaceutical companies have increased their use of wholesalers, even in concentrated market areas, because of the high customer service levels required. 

Narcissus comprises approximately 80-100 wild species of perennial geo-phytes, geographically concentrated in southwestern Europe, with a center of diversity in the Iberian Peninsula and North Africa, which substantiates the hypotheses that landmasses of Europe and Africa were once joined. A few species extend into France and Italy, and even fewer are found in the Balkans and the eastern Mediterranean. Records outside this area, such as N. tazetta variants in China and Japan, are almost certainly ancient introductions 3,4). The native habitats of Narcissus species are very varied, ranging from lowland to mountain sites, including grassland, scrub, woods, river banks, and rocky crevices (J). Most of the species... 

There is no doubt that taken as a whole, the chemical industry is truly a global industry. As noted earlier in section 2, Western European firms were the first to move overseas. U.S. firms have tended to be a bit slower, mainly on account of the large domestic market. Japanese firms have tended to lag both. Indeed, if we examine the median index of geographical concentration (table 11 column E), the same picture emerges. Large European firms are the most globalized (least geographically concentrated in their investments) followed by the U.S., and Japanese firms, in that order. 

Occurrence Chromium is practically only found as chromite or chrome iron stone, (FeCr204), in open-pit mining or in near-surface underground mining. Metallic chromium is obtained by reduction of the ore with aluminum or silicon. Untapped chromite deposits are plentiful and geographically concentrated in Kazakhstan and southern Africa. 

Whereas cities are efficient geographic concentrators of chemicals, they are not efficient at retaining these emissions. As noted above, the key reason that urban environments are efficient at exporting rather than retaining chemical emissions is the abundance of impervious surfaces that act as transient, but not permanent chemical... 

The formation of clusters can be a way to increase companies performance. Porter [4] defines a cluster as a geographic concentration of mutually interconnected companies, specialized suppliers, providers of services, companies in similar fields and associated institutions, such as universities, agencies and associations of different orientations, which compete, but also cooperate. Clusters may represent forms of vertical as well as horizontal integration of companies. 

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