Iron biogeochemical cycle

Fig. 6.5 Microbial iron and sulfur cycles that may have dominated biogeochemical cycling before the origin of oxygenic photosynthesis, aerobic respiration and possibly before the use of oxides of nitrogen.

We can see that the soluble and exchange forms of these metals are present in small amounts accounting merely for a few percent of the total metal content in soil. The content of organometal species is relatively high in the upper profile rich in humic species, whereas it drops sharply in the mineral horizons. Copper is extensively involved in the biogeochemical cycle in the Forest ecosystems and this is less profound for cobalt. It is noteworthy that a large part of metals (in particular, of copper) become bound to iron hydroxides. This is typical for various trace elements, including arsenic, zinc and other elements with variable valence. 

ISOTOPIC VARIATIONS PRODUCED DURING BIOGEOCHEMICAL CYCLING OF IRON... 

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Biogeochemical cycle of iron in the crustal-ocean-atmosphere factory. Source-. After Achterberg, E. R, et al. (2001). Analytics Chemica Acta 442, 1-14. 

Considerable evidence exists that human activities have already perturbed parts of the interlinked global biogeochemical cycles of the nutrients, micronutrients, carbon, and O2. Some of these perturbations are the consequence of climate change and others are associated with changes in the rates of input of nutrients and iron to the sea. As... 

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Even though iron is the fourth most abundant element in the Earth s crust, only a small portion is available for biogeochemical cycling which consists largely of oxidation—reduction reactions of ferric to ferrous ions and vice versa. These reactions are important in organic and inorganic iron-containing compounds. 

Fig. 64. Scheme of vertical zoning and biogeochemical cycle of iron in the formation of iron-rich sediments (pH = 6 siderite, greenalite, and hydrogoethite are diagenetic, magnetite crystalline). 

Johnson, K. S., et al. (2003). Surface ocean - lower atmosphere interactions in the Northeast Pacific Ocean gyre Aerosols, iron and the ecosystem response. Glob. Biogeochem. Cycles. 17, 10.1029/... 

Moore, J. K., Doney, S. C., and Lindsay, K. (2004). Upper ocean ecosystem dynamics and iron cycling in a global three-dimensional model. Global Biogeochemical Cycles. 18, 10.1029/2004GB002220. 

Sedwick, P. N. and others (2005). Iron in the Sargasso Sea (Bermuda Atlantic Time-series Study region) during summer Eolian imprint, spatiotemporal variability, and ecological implications. Global Biogeochem. Cycles 19, doi 10.1029/2004GB002445. 

Dugdale, R. C., Wilkerson, F. P. (1990). Iron addition experiments in the Antarctic, a reanalysis. Global Biogeochem. Cycles 4, 13—19. 

Snyder, M., TaiUefert, M., and Ruppel, C. (2004). Redox zonation at the sahne-influenced boimdaries of a permeable surficial aquifer Effects of physical forcing on the biogeochemical cycling of iron and manganese. J. Hydrol. 296, 164—178. 

Lefevre, N., and Watson, A. J. (1999). Modehng the geochemical cycle of iron in the oceans and its impact on atmospheric CO2 concentrations. Global Biogeochem. Cycles 13(3), 727—736. 

Parekh, P., Follows, M. J., and Boyle, E. (2004). Modeling the global ocean iron cycle. Global Biogeochem. Cycles 18(1), doi 10.1029/2003GB002061. 

Fung, l.,Meyn, S., Tegen, I., Doney, S.,John,J., and Bishop,J. (2000). Iron supply and demand in the upper ocean. Global Biogeochem. Cycles 14, 281-295. 

Martin, J. (2002). Iron as a limiting factor in oceanic productivity. In Primary Productivity and Biogeochemical Cycles in the Sea (Falkowski, P., and Woodhead, A., eds.). Plenum, New York, pp. 123-138. 

Boyd, P. W., Wong, C. S., Merrill, J., Whitney, F., Snow, J., Harrison, P. J., and Gower, J. (1998). Atmospheric iron supply and enhanced vertical carbon flux in the NE subarctic Pacific Is there a connection Global Biogeochem. Cycles 12(3), 429—441. 

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