Chemistry /chemical cycles

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. 

Chemistry is also used to transform complex, although biodegradable, wastes into simpler products that can be easily incorporated in the biogeo-chemical cycle of the elements. It is often used to mimic natural chemical or biochemical processes under human-controlled circumstances. In optimal conditions these processes are kinetically favored, achieve high efficiencies, and completion of the reactions in shorter times as compared to the corresponding natural rates of change. This ideally leads... 

A recent laboratory comparison of the shape of the water of hydration bands with the spectra obtained by the Galileo spacecraft indicates that the hydrated material mentioned above might in fact be frozen, hydrated H2S04. This material would be produced by the charged particle irradiation of sulfate salts, sulfur or SO2 in an ice matrix. Therefore, a sulfur chemical cycle is maintained by the incident radiation, a cycle similar to that occurring at higher temperatures in the atmospheres of the Earth and Venus. On Europa, this involves oxidants such as SO ", H202 and 02 which have potential importance for the proposed prebiotic chemistry. 

Having examined the chemistry of estuarine environments, we now turn to global chemical cycling in the open ocean. This chapter began by noting that the major ion chemistry of seawater is different from that of continental surface waters (Table 6.1). Three principal features clearly mark this difference ... 

The chemistry of dissolved metals in seawater can be grouped into three classes, which describe the behaviour of the metal during chemical cycling. These classes—conservative, nutrient-like and scavenged—have been recognized by the shapes of concentration profiles when plotted against depth in the oceans. 

Figure 5.2. Stratospheric chemical cycle affecting odd oxygen species in the stratosphere. The numbers in boxes represent concentrations (cm-3) calculated at 25 km altitude while the numbers associated with the arrows account for the reaction fluxes (cm-3s-1) between different compounds (24 hour global average conditions). Note that the figure extends beyond the simple pure oxygen chemistry case and that NO2 is identified as an odd-oxygen reservoir. (See following sections for more details from Zellner, 1999).

Flo. 3. Chemical cycles affecting the formation and decay of chlorine oxide trace species in the earth s atmosphere (reproduced with permission from Wayne, R. P. Chemistry of Atmospheres, 2nd ed., p. 137, Clarendon Press Oxford, 1991). 

Much of this chapter will be devoted to carefully working through the chemistry of stratospheric O3 depletion. Depletion occurs as a result of chemical cycles in which the reactive entity is regenerated over and over. One such cycle that results after the release of a Cl atom from photolysis of one of the molecules in Figure 5.1 is... 

Figure 8.4 Schematic showing the chemical cycling of the gas-phase halogens (iodine highlighted in dark gray) in the atmosphere, and the links to aerosol formation and chemistry (adapted from Saiz-Lopez and Plane, 2004a).

Khalid, R. A., R. P. Gambrell, and W. H. Patrick, Jr. 1978. Chemical transformations of cadmium and zinc in Mississippi River sediments as influenced by pH and redox potential. In D. C. Adriano and I. L. Brisbin, Jr. (eds.) Environmental Chemistry and Cycling Processes. Department of Energy, Symp. Ser. 45 417-433. Tech. Info. Center, U.S. Department of Energy. Proc. 2nd Mineral Cycling Symp., May 1, 1976. 

Bioinorganic Chemistry Carbon Cycle Climatology Greenhouse Eeeect and Climate Data Nitrogen Cycle, Biological Ozone Measurements AND Trends Planetary Atmospheres Transport and Fate oe Chemicals in the Environment Tropospheric Chemistry... 

Bioinorganic Chemistry Carbon Cycle Greenhouse Effect and Climate Data Greenhouse Warming Research Nitrogen Cycle, Atmospheric Ocean-Atmospheric Exchange Pollution, Environmental Soil and Groundwater Pollution Transport and Fate of Chemicals in the Environment... 

ManciniN.D.,MitsosA. Conceptualdesign and analysisofITMoxy-combustion power cycles , Physical Chemistry Chemical Physics,13(48), 21351-21361,2011, doi 10.1039/C1CP23027A. 

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