Geochemical cycle figure

Medical geochemistry (also referred to as environmental geochemistry and health Smith and Huyck (1999), Appleton et al. (1996)) can be considered as a diverse subdiscipline of medical geology that deals with human and animal health in the context of the Earth s geochemical cycle (Figure 1). Many medical geochemistry studies have focused on how chemical elements in rocks, soils, and sediments are transmitted via water or... 

Figure 1.22 Geochemical cycle of uranium showing relationships of ore deposits and most important form of uranium in various parts of the cycle.

Figure 3. General model of bio geo chemical cycles in the Earth s ecosystems. The left part is bio geochemical cycling in terrestrial ecosystems, the right part is aquatic ecosystems and the central part is connected with the atmosphere. The fine solid lines show the biogeochemical food webs (the Latin numbers I-XXI) and directed and reverse relationships between these...

Figure 1. Schematic illustration of the bio geochemical cycling processes in Forest ecosystems (Nihlgard et al., 1994).

Figure 3. The general nitrogen model for illustrating the bio geochemical cycling in Forest ecosystems. Explanations for the fluxes 1, ammonia volatilization 2, forest fertilization 3, N2-fixation 4, denitrification 5, nitrate respiration 6, nitrification 7, immobilization 8, mineralization 9, assimilatory and dissimilatory nitrate reduction to ammonium 10, leaching 11, plant uptake 12, deposition N input 13, residue composition, exudation 14, soil erosion 15, ammonium fixation and release by clay minerals 16, biomass combustion 17, forest harvesting 18, litterfall (Bashkin, 2002).

Figure 6. Carbon bio geochemical cycle in the hypothec forest ecosystem (Schulze, 2000). 

Figure 1. Bio geochemical cycle and exposure pathways in Tropical rain Forest ecosystems.

The findings are summarized below, and in Figures 6, 7 and 8. Complete references are provided in the text and in the figure captions. Implications of these data for understanding Mo geochemical cycling, and for application of this understanding to paleoredox questions, are discussed in the subsequent section. 

Many diverse processes are involved in the transformation of the elements and their compounds in the Earth. Some of the pathways observed are shown in Figure 1, a version of the so-called geochemical cycle . This cycle is very much simplified and is not a closed one. It may also be short-circuited and indicated processes may be very fast on the geological time scale, or, more often as not, occupy very lengthy periods, amounting in some cases to billions of years. 

Figure 10.14. The geochemical cycle of strontium. The values within the boxes are the mean 87Sr/86Sr ratios of the contained strontium. Estimates of total Sr flux for various flows are also shown. (After Holland, 1984.)...

Figure 10.31. Schematic diagram of a three-box (reservoir) model of a closed-system geochemical cycle of a substance (e.g., carbon). The reservoir masses are designated Mi, M2, and M3, and the rates of transfer (fluxes) of a substance between boxes are shown as Fy, where i and j = 1,2,3, but i j. The mass balances for the three reservoirs are given by the three differential equations, kjj are first-order rate constants (units of 1/T) and T is time.

Figure 10.38. Model of CO2-O2 geochemical cycling describing interrelationships on a several thousand to 100 million year time basis. Fluxes resulting from the various processes shown are in units of 1012 moles y-1. (After Gairels et al., 1976.)...

Figure 10.39. Perturbation of the CO2-O2 geochemical cycle illustrated in Figure 10.38. In this case, the perturbation was a doubling of the carbon flux related to marine productivity. Changes in reservoir masses and the carbon flux to the seafloor are shown as a function of time. (After Garrels et al., 1976.).

Figure 10.40. Comparison of a model calculation (solid line) for glacial-interglacial changes in atmospheric CO2 with the observed CO2 record (dashed line) from the Vostok ice core. The model is that of the CO2-O2 geochemical cycle in Figure 10.38.

Figure 10.41. Schematic diagram of processes involved in the carbonate-silicate geochemical cycle. (After Berner and Lasaga, 1989.)... 

Figure 10.42. A quantitative box model of the carbonate-silicate geochemical cycle. Reservoir masses are in units of 1018 moles, and fluxes in units of 1018 moles per million years. Comparison with Figure 10.32 gives some idea how flux values and portrayal of the cycle have changed during the last decade and a half. (After Lasaga et aJ., 1985.)...

Figure 10.43. Results of model calculations of the carbonate-silicate geochemical cycle illustrated in Figure 10.42. The corresponding changes in atmospheric CO2 and temperature during the last 100 million years are evident. Notice how organic carbon burial may play a strong role as a negative feedback mechanism for a perturbation in atmospheric CO2 driven by tectonics. (After Lasaga et al., 1985.)...

It is not surprising that the geochemical cycle of sulfur during the I0W-O2 Archean differed from that of the present day. As shown in Figure 5, the mass-dependent fractionation of the sulfur isotopes in sedimentary sulfides was smaller prior to 2.7 Ga than in more recent times. Several explanations have been advanced for this observation. The absence of microbial sulfate reduction is one. However, the presence of... 

Figure 1). The solute exchanges resulting from reactions in surface sediments can be important for the chemistry of oceanic deep water, and to the overall cycles of several elements in the oceans. In addition, the alteration of particles by these reactions must be taken into account when down-core records of the accumulation of sedimentary components are interpreted in terms of past oceanic and atmospheric chemistry. Understanding early diagenetic reactions in the upper few centimeters of the marine sediment column is important both to the study of geochemical cycles in the contemporary ocean and to the reconstruction of past oceanic conditions. 

Figure 14 The simplified geochemical cycles of carbon and sulfur, including burial and weathering of sedimentary carbonates, organic matter, evaporites, and sulfides. The relative fluxes of burial and weathering of organic matter and sulfide minerals plays a strong role in controlling the concentration of atmospheric O2.

Figure 15.17. The interdependence of the geochemical cycles of C, N, and O. The interlocking of the global chemical cycles illustrates the stationary state that prevailed in regulating our environment for the last 600 million years. Reservoir areas are proportional to the size of the inventories (the number of moles contained) for example, SiOz = 220 X 10 mol, CaC03 = 50 x 10 mol, and Oj = 0.38 x 10 ° mol. The circled numbers refer to the processes given in equation 23-26. The numbers of the interconnecting branches refer to steady-state material fluxes in 10 moP. (Adapted from Garrels and Perry, 1974.)...

The inventories are most important for our ecosystems. O2 and CO2 are very small in comparison to reservoirs of the minerals in Figure 15.17. The reservoirs of O2 and CO2 are interconnected with numerous very large reservoirs. In the clockwork, so to speak, the rapidly turning wheels of CO2 and O2 are interlocked with extremely slowly turning wheels of sediment components. The interdependence of these geochemical cycles and their synchronization determine the composition of the oceans and are to a large extent responsible for the maintenance of a constant composition of the atmosphere. 

By way of summarizing some of the conclusions reached in the preceding sections, an attempt has been made to show the geochemical cycle with special reference to uranium. For this reason, the way of presenting the cycle differs from that commonly used (e.g. Mason, 1966). Figure 8.3a shows the cycle itself while in Fig. 8.3b are shown the author s assessment of the relationship of ore deposits to the geochemical cycle, and also the most important form of the uranium at each stage of the cycle. 

Figure 8.5 Mean monthly concentrations of atmospheric CO2 at Mauna Loa, Hawaii. The yearly oscillation is explained mainly by the annual cycle of photosynthesis and respiration of plants in the Northern Hemisphere. From E, K. Berner and R. A. Berner. Global environment Water, air, and geochemical cycles. Copyright 1996. Used by permission of Prentice Hall, Inc., Upper Saddle River, NJ.

Figure 1 (A) Dissolved vanadium in the North Pacific Ocean, 11 °N, 140°W. (Data from Collier RW (1979) Particulate and dissolved vanadium in the North Pacific Ocean. Nature 309 441 44.) (B) Dissolved molybdenum in the North Pacific Ocean, 30°N, 159°50 W. (Datafrom Sohrin Y, Isshiki K and Kuwamoto T (1987) Tungsten in North Pacific waters. Marine Chemistry22 95-103.) (C) Dissolved tungsten in the North Pacific Ocean, 30°N, 159°50 W. (Data from Sohrin Y, Isshiki Kand Kuwamoto T (1987) Tungsten in North Pacific waters. Marine Chemistry22-. 95-103.) (D) Dissolved rhenium in the North Pacific Ocean, 24°16 N, 169°32 W. (Data from Colodner D, Sachs J, Ravizza G, Turekian K, Edmond J and Boyle E (1993) The geochemical cycle of rhenium a reconnaissance. Earth and Pianetary Science Letters 117 205-221.)...

Figure 1 Idealized plot of transfer coefficient (Kw) as a function of wind speed (u) and friction velocity (u ). (Adapted with permission from Liss PS and Merlivat L (1985) Air-sea gas exchange rates. In Buat-Menard P (ed.) The Role of Air-sea Exchange in Geochemical Cycling, p. 117. NATO AS I Series C, vol. 185. Dordrecht Reidel.)...

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