Biogeochemical cycles, understanding

Mercury provides an excellent example of the importance of metal speciation in understanding biogeochemical cycling and the impact of human activities on these cycles. Mercury exists in solid, aqueous, and gaseous phases, and is transported among reservoirs in all these forms. It undergoes precipitation-dissolution, volatilization, complexation, sorption, and biological reactions, all of which alter its mobility and its effect on exposed populations. The effect of all... 

Disturbance of Phosphorus Biogeochemical Cycle in Agrolandscapes Conceptual ideas behind simulation of P cycling are related to construction of models for freshwater terrestrial ecosystems and a generalized oceanic system and understanding the restrictions of its application. 

Selected applications of isotope ratio monitoring technique in mass spectrometry to geochemistry, biology, medicine and other areas of science are described. It was shown that gas isotope ratio mass spectrometry has greatly increased our understanding of the biogeochemical cycles of C, N, S and H2O in natural and agricultural ecosystems. 

Keene, W. C., and J. N. Galloway, The Biogeochemical Cycling of Formic and Acetic Acids through the Troposphere An Overview of Current Understanding, Tellus, 40B, 322-334 (1988). 

In essence, measurements of these nitrogen species are required to understand the several biogeochemical cycles that transport material through the... 

Understanding of biogeochemical cycling and trophic interactions is often hindered by the nature of budgetary approaches to ecosystem study (16). For example, many estimates of element flux are made by difference (e.g., between inflow and outflow) or are inferred from indirect evidence... 

Both N and P are important heteroatoms in DOM from the perspective of understanding biogeochemical cycles within catchments. All organisms require N and P for growth, and these nutrients are present in detrital organic material in soil and sediments. Thus, the incorporation of N- and P-containing moieties is likely to occur as an inherent aspect of DOM production and represents a potentially important pathway by which these... 

Inland water systems are more diverse and dynamic than marine systems (see Chapter 18) therefore, it becomes apparent that more emphasis should be placed on understanding microbial community dynamics in these highly variable systems. Lakes and rivers are intimately associated with their watersheds and hence receive a large influx of material from the surrounding terrestrial environments. This linkage affects the biogeochemical cycles and processes within the system as oftentimes members of the terrestrial community end up in the aquatic environment. 

In an attempt to understand the factors that determine the feedbacks from the global nature-society system of the cycles of carbon and other chemicals, we construct a hierarchy of model units to parameterize all the known physical and biogeochemical processes that are responsible for the transport of various substances. We substantiate these units by means of partial models which estimate the balance between relationships at the boundaries of different media. The correlations between biogeochemical cycles and the many activities of human society are the basic objectives of this book. 

Studies of the modem global biogeochemical cycle of carbon form one basis for understanding the geologic history of atmospheric CO2. In turn, these investigations of the history of carbon dioxide in the atmosphere provide knowledge that can be used to interpret the future of atmospheric CO2 levels and... 

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