Effect on geochemical processes

Messineva, M.A., The geological activity of bacteria and its effect on geochemical processes, in Geologic Activity of Microorganisms, Kuznetsov, S.I., Ed., Transactions of the Institute of Microbiology No. IX (trans. from Russian), Consultants Bureau, New York, 1962, pp. 6-24. 

Effects on Geochemical Processes at the Mineral-Water Interface... 

DeMaster DJ, Kuehl SA, Nittrouer CA (1986) Effects of suspended sediments on geochemical processes near the mouth of the Amazon river - examination of biological silica uptake and the fate of particle-reactive elements. Cont Shelf Res 6 107-125... 

This normalization process helps highlight the effects of geochemical processes on the separation of this group of very similar elements (12, 19). 

Clearly, the role of zooplankton in sedimentation of material is of great interest beyond biology (for example, 69), and there are interesting questions concerning the effects of the behavior of organisms on geochemical processes. For example, work on particulate radionuclides indicates that carbonate is sedimented in larger (or at least faster sink-ing) particles than is iron (70) one would like to know whether selective... 

Effects of pH on Deep-Well Geochemical Processes and Other Environmental Factors... 

Several studies investigating the environmental effects of controlled tyre combustion have been conducted. It is evident that atmospheric emissions can be greatly reduced if proper air pollution control systems are installed. Laboratory and field data provide evidence indicating that concentrations of some environmental pollutants, especially NOx, may decrease due to tyre combustion, whereas others increase compared to pure coal combustion. Zinc is an example of an element that increases in both solid combustion products and atmospheric emissions. The geochemical impact of higher Zn contents in fly and bottom ash on leaching processes in disposal sites remains to be tested. 

Differentiation is among the most important geochemical processes that affected planets. We have already discussed the differentiation of planetesimals in Chapter 11 here we will consider differentiation in large planets, which differs because of longer duration and the effects of significantly higher pressures. Specifically, we will focus on the Earth, since we know most about it. A complete discussion of the Earth s differentiation is beyond the scope of this book, and readers are referred to reviews of this topic (e.g. Halliday, 2004 Tolstikhin and Kramers, 2008 Halliday and Wood, 2009) for more detailed information. 

Sulfur isotopes can effectively be used to examine important geochemical processes associated with redox changes in sedimentary environments. The speciation of sulfur is strongly affected by redox potential, pH, productivity, microbial sulfate reduction, and iron availability (Berner, 1984). More details are provided on the sulfur cycle in chapter 12. In general, during microbial dissimilatory sulfate reduction there is fractionation of sulfur... 

The prominent niobium and lead spikes of continental materials are not matched by any of the OIBs and MORBs reviewed here. They are, however, common features of subduction-related volcanic rocks found on island arcs and continental margins. It is therefore likely that the distinctive geochemical features of the continental crust are produced during subduction, where volatiles can play a major role in the element transfer from mantle to crust. The net effect of these processes is to transfer large amounts of lead (in addition to mobile elements like potassium and rubidium) into the crust. At the same time, niobium and tantalum are retained in the mantle, either because of their low solubility in hydrothermal solutions, or because they are partitioned into residual mineral phases such as Ti-minerals or certain amphiboles. These processes are the subject of much ongoing research, but are beyond the scope of this chapter. 

Copper was selected as the first metal for which to attempt to optimize the shipboard analyses because considerable information is available about the marine chemistry of copper, and because this new analytical capability would greatly enhance our ability to study copper in the ocean. The concentration of copper in the ocean varies from 0.5 to 5 nmol/kg in response to biological and geochemical processes (Table I). The chemical speciation of copper has received considerable attention because the biological effects of copper depend on its chemical form (i-3). The principal forms of copper include inorganic complexes such as CUCO3, CuHCO , CuOH, and organically bound copper (4, 5). 

---