Primary producers

Canada, the United States, and South America are the principal exporters of cryoHte and Russia and Europe import cryoHte. Primary producers in North America are Alcan, Alcoa, and Reynolds Aluminum. The 1993 price of recovered-grade cryoHte, which has as impurity, was 400/t, and of... 

Outside of the United States, there are six primary producers in China, France, Mexico, Morocco, South Africa, and Spain. Mines in Newfoundland, Canada, were closed in 1990. Both Mexico and South Africa have lost market share to China which has high grade, low cost fluorspar. China is expected to dominate world markets because reserves are vast and production cost is low. Table 3 (2) shows a Hst of world producers by country of fluorspar in the early 1990s. 

Gum Karaya. Gum karaya [19000-36-61] or sterculia gum is the dried exudate of the Sterculia urens tree, which is now cultivated in India, the primary producing area. The best quahty gum is collected by tapping the trees during the period April to June with a second collection of lower quahty product later in the year. The gum is allowed to dry on the trees, and the cmde gum is collected and sorted according to color and purity. It is further sorted and processed to powdered gum karaya in the country of use. The quahty of supphes varies greatly (43). 

Nylon-6 [25038-54-4] was first made in 1899 by heating 6-aminohexanoic acid (143), but its commercially feasible synthesis from caprolactam was discovered by Paul Schlack at 1. G. Farbenindustrie in 1938. Like nylon-6,6, it is a tough, white translucent, semicrystalline sofld, but melts at a lower temperature (T = 230° C. The physical properties and primary producers of nylon-6 are Hsted in Tables 9 and 10, respectively. 

Production. Production of polycarbonate has steadily iacreased siace the opening of the first commercial plants ia the early 1960s. Worldwide capacity reached 665,000 t ia 1992 (38). Siace the mid-1980s, productioa has iacreased at 8—13% per year. Expected capacity ia 1995 is over oae million metric toas. Plants have opened ia several couatries, including Japan, Chiaa, Korea, and Brazil, although as of this writing (1995) the United States remains the primary producer of polycarbonate. U.S. production is about 47% of that worldwide. 

Bayer aluminum hydroxides in most grades are sold by all major U.S. alumina producers. Other firms offering aluminum hydroxide fillers probably operate reprocessing faciHties to grind or otherwise treat hydroxide obtained from the primary producers. Countries exporting small amounts to the United States are Japan, Germany, Canada, and the UK. 

The supply and demand for mbidium compounds has grown steadily since the 1970s. In 1979 the U.S. demand was ca 1040 kg of contained mbidium (16), and total world demand was estimated at approximately twice that of the United States. Reserves of mbidium in North America are estimated at 2 X 10 kg the United States is - 100% import-reliant for mbidium, and Canada is the principal source of the raw material (16). The demand for mbidium metal is small compared to the demand for mbidium compounds. Table 2 fists approximate prices of mbidium metal and mbidium compounds. Primary producers of mbidium are Cabot Performance Chemicals (Boyerstown, Pennsylvania), MSA Research Corporation (Callery, Pennsylvania), and CM Chemical Products, Inc. (Berkeley Heights, New Jersey). Research quantities of mbidium in standard and specialized ampuls are available from Strem Chemicals, Inc. (Newburyport, Massachusetts). 

Applications. In 1994, approximately 675,000 metric tons of amorphous precipitated sihca were manufactured for sale (38,62). Degussa, J. M. Huber, and PPG in the United States and in Europe, and Akzo (Germany), Aluflour (Sweden), Crosfield (United Kingdom), Nippon Sihca (Japan), Rhc ne-Poulenc (France), Shionogi (Japan), Tokuyama Soda (Japan), and Vitro PQ (Mexico) are the primary producers. 

The two largest global producers of trichlorosilane are Wacher in Europe and Dow Coming in the United States. In addition, there are three primary producers in Japan Tokuyama Soda, Mitsubishi Materials, and Osaka Titanium. 

Sucrose reacts with fatty acids to produce esters with degrees of esterification (DE) from 1 to 8 and hydrophi1 ic /Iipophi1 ic balances that provide them with numerous appHcations. Primary producers are Japan and the Netherlands, with total production at 6000 t/yr. Sucrose esters are nontoxic and biodegradable, and are approved for use in the EC, Japan, and the United States. 

In general, the production of fused materials is much more energy intensive than that of hydrated products, and this difference is reflected in their prices. The primary producers are the United States Borax Chemical Corp. and the North American Chemical Co. Yearly fusion capacities for the two companies ate reported to be 86,000 and 36,000 metric tons B2O2, respectively (6). There is a plant in Turkey designed for the production of 60,000 t/yr of refined anhydrous borax from tincal ore (102). Small quantities of anhydrous borax have been produced in Argentina. 

Some of the more prominent carboxyhc acids that are not fat- or oil-based include acetic, acryUc, and olefin-based propionic, butyric/isobutyric, 2-ethylhexanoic, heptanoic, pelargonic, neopentanoic, and neodecanoic. Table 1 summarizes the production, pricing, and primary producers of these acids. 

The primary producer of cesium metal in the United States is Cabot Corp. 

There are nine primary producers of ch oline chloride within the world. These are Hsted in Table 1. There are also small producers located in Taiwan and the People s RepubHc of China. 

The primary producers of ethyl alcohol also market the specially denatured and completely denatured alcohols, as well as various proprietary solvents in which ethyl alcohol is the basic ingredient. These various products can also be described by rigid and descriptive specifications, but the... 

Cogeneration is an energy conversion process wherein heat from a fuel is simultaneously converted to useful thermal energy (e.g., process steam) and electric energy. The need for either form can be the primary incentive for cogeneration, but there must be opportunity for economic captive use or sale of the other. In a chemical plant the need for process and other heating steam is hkely to be the primaiy in a pubhc utility plant, electricity is the usual primary produc t. 

FIGURE 1.2 The food pyramid. Photosynthetic organisms at the base capture light energy. Herbivores and carnivores derive their energy ultimately from these primary producers. 

Blowing air through the hot, crude, liquid metal oxidizes traces of metals such as Fe, Cu, Zn and Pb which form an easily removable scum. Further purification is by distillation under reduced pressure. About 4000 tonnes of mercury are used annually but only half is from primary, mine production the other half being secondary production and sales from stockpiles. The main primary producer is now Spain, but several other countries, including the former Soviet Union, China and Algeria, have capacity for production. 

The early promise of wide applications for beryllium has not materialised, despite improvements in purity and more efficient means of consolidation such as isostatic hot pressing, because of the metal s toxicity, brittleness and cost. It is now chiefly of interest in the specialised fields of aerospace and nuclear applications. BrushWellman is currently the sole commercial primary producer of beryllium metal in the West. 

Organic matter Accumulation of organic matter Bacteria Primary producers Slowed down decomposition High oxygen consumption High mineralization... 

Sediments Siltation Primary producers Invertebrates Fish Reduced production Changes in community composition Difficulties in gas diffusion... 

Nutrient Higher concentration eutrophication Primary producers Potential bottom up-effects Higher gross primary production Lower efficiency on materials processing... 

Hill WR, Stewart AJ, Napolitano GE. 1996. Mercury speciation and bioaccumulation in lotic primary producers and primary consumers. Can J Fish Aquat Sci 53 812-819. 

Other roles for noxious metabolites produced by certain phytoplankton species include mediation of allelopathic interactions [47]. Allelopathy covers biochemical interactions among different primary producers or between primary producers and microorganisms. These can provide an advantage for the producer in the competition among different photoautotrophs for resources. Although not directly involved in chemical defense, allelopathic metabolites can affect the dominance and succession of species in phytoplankton therefore they are crucial for understanding plankton composition. In contrast to the fresh water environment, the location of many studies on the role of allelopathic interactions, which have identified active compounds [47], only few studies have addressed this topic in the marine environment. 

Few studies have addressed the dynamics of suspended and attached primary producers in the Ebro basin. Previous data on phytoplankton assemblages are available only for the Ebro delta [6], and for phytoplankton occurring in the lower course of the river [7, 8]. However, there is no information about other... 

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