Metals ocean productivity

The air emissions of fossil fuel combustion are dispersed and diluted within the atmosphere, eventually falling or migrating to the surface of the Earth or ocean at various rates. Until recently, most attention was focused on the so-called primary pollutants of fossil fuel combustion that are harmful to human health oxides of sulphur and nitrogen, carbon monoxide, suspended particles (including soot), heavy metals, and products of incomplete combustion. These pollutants are most concentrated in urban or industrialized areas close to large or multiple sources. However, the primary pollutants may interact with each other, and with atmospheric constituents and sunlight, forming secondary pollutants that disperse far beyond the urban-... 

Because of the importance of diatoms in oceanic productivity, silicon is an important algal nutrient in seawater. A transporter of Si(OH)4 has been isolated and sequenced (Hildebrand et al, 1998 Hildebrand et al, 1997) and the physiology of silicon uptake has been well studied (Martin-Jezequel et al, 2000). Nonetheless, the molecular mechanism of Si(OH)4 transport and silica fmstule formation in diatoms are still largely mysterious. From indirect evidence, it appears possible that the Si(OH)4 transporter may contain zinc, coordinated to cysteines, as a metal center in the portion of the protein exposed to the outside of the cell (Hildebrand, 2000 Rueter and Morel, 1981). If true, this would be an unusual example of a transport protein functioning with a metal center. 

Estimates of potential trace metal oceanic input based on atmospheric washout, mining productivity figures, and relative river transport are given in Tables 1 and 2. 

Carbon Cycle. Metal Pollution. Tracers of Ocean Productivity. 

Clay Mineralogy. Hydrothermal Vent Deposits. Platinum Group Elements and their Isotopes in the Ocean. Pore Water Chemistry. Rare Earth Elements and their Isotopes in the Ocean. River Inputs. Tracers of Ocean Productivity. Transition Metals and Heavy Metal Speciation. Uranium-Thorium Decay Series in the Oceans Overview. 

Most lead used by industry comes from mined ores ("primary") or from recycled scrap metal or batteries ("secondary"). Human activities (such as the former use of "leaded" gasoline) have spread lead and substances that contain lead to all parts of the environment. For example, lead is in air, drinking water, rivers, lakes, oceans, dust, and soil. Lead is also in plants and animals that people may eat. See Chapter 3 for more information on the physical and chemical properties of lead. Chapter 4 contains more information on the production and use of lead. 

Bruland, K. W., Donat, J. R. and Hutchins, D. A. (1991). Interactive influence of bioactive trace metals on biological production in oceanic waters, Limnol. Oceanogr., 36, 1555-1577. 

Kenneth Johnson is a Senior Scientist at the Monterey Bay Aquarium Research Institute. His research interests are focused on the development of new analytical methods for chemicals in seawater and application of these tools to studies of chemical cycling throughout the ocean. His group has developed a variety of analytical methods for analyzing metals present at ultratrace concentrations in seawater. His expertise lies in trace metal analysis and instrumentation. The creation of reference materials to calibrate these instruments is important for the production of long-term, high-precision datasets. Dr. Johnson has participated on the NRC Committee on Marine Environmental Monitoring and the Marine Chemistry Study Panel. 

In contrast to their rather low dissolved concentrations in seawater, some of the trace metals, e g., iron and aluminum, along with oxygen and silicon, comprise the bulk of Earth s crust. Some trace elements are micronutrients and, hence, have the potential to control plankton species composition and productivity. This provides a connection in the crustal-ocean-atmosphere fectory to the carbon cycle and global climate. 

The products are thermodynamically favored under the oxic alkaline conditions that are characteristic of most of the ocean. Reaction rates are slow, so metal oxides tend to precipitate onto detritus or preexisting nodules because of the catalytic effect of the surfaces. The Fe and Mn are supplied by both river and hydrothermal sources. For Mn, these two sources are about equal. 

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