Phosphorus natural cycles

Photoelectron.—n-Orbital energies appear to be unsuitable to discern the aromatic nature of phospholes (120) due to combined nn and ttn interactions. It is concluded that n conjugative and P-Cw hyperconjugative interactions stabilize the phos-phole system relative to the interrupted cw-butadiene and phosphorus subunits, and that the p.e. spectrum can be interpreted in favour of an aromatic phosphole ring.143 Other workers have discussed144 and reviewed145 this aromaticity problem, and there has been a quantum-chemical study of the aromatic nature of phosphorus hetero-cycles.144 The p.e. spectrum of the ylide (121) contains peaks at 6.19, 8.32, and... 

Griffith, E.J. Modem mankind s influence on the natural cycles of phosphorus. In Phosphorus and the Environment Ciha Poundation, New Series, 57, 1978. 

Phosphorus in the Natural Environment Phosphorus takes part in three natural cycles within the environment (Emsley 1977). The first of these is the inorganic cycle, comprising phosphorus in crust of the Earth, where its content is about 10 tons, mainly in the form of mineral apatite, Ca5(P04)3(F, Q). From this source, the phosphorus is released into more soluble forms due to the process of rock weathering. 

There are two quite different aspects to be taken into account when assessing the utilization of the element. One is to think of the many ways in which nature cycles phosphorus through the environment - broadly speaking this is out of our control, though as will be noted, there is ample opportunity for pollution concerns involving this element. The other is to think of ways in which we can utilize the element industrially or in the laboratory. This section will provide a brief introduction to both areas. 

Under forest fallow the rate of turnover of the nutrient elements is very rapid, according to Nye and Greenland (1960), and after a few years exceeds the rate of storage in the fallow. In addition to the nutrients in the litter fall, considerable phosphorus and potassium are leached from the green leaves, and the dead wood contains considerable calcium. About five tons per acre of dry litter falls on the soil annually, and most of it decomposes rapidly. The amount of nutrients added in the rain and as dust is very small in comparison with the amounts involved in natural cycling. 

Arsenic is present mainly as arsenate in trace quantities of the element that are found in seawater and in life cells. Comparatively little is known about the natural cycle of this element, which may to some extent be associated with that of phosphorus. Trace quantities may be necessary for some life processes (Chapter 11). 

E.J. Griffiths, Mankind s influence on the natural cycle of P, in Phosphorus in the Environment, Ciba Foundation Symposium No. 57, Elsevier, Amsterdam, 1978. 

While the trace-element content of guano and, to a lesser extent, of mined mineral salts, could make some contribution to the nutrient requirements of crops, these materials are no longer adequately available. We have now become largely dependent on highly purified compound fertilisers containing only nitrogen, phosphorus and potassium as nutrients, so that the rate of depletion of essential trace elements has been greatly accelerated. The natural cycle... 

Soderlund, R. and Svensson, B. H. (1976). The global nitrogen cycle. In "Nitrogen, Phosphorus and Sulfur - Global Cycles" (B. H. Svensson and R. Soderlund, eds), Ecol. Bull. No. 22, pp. 23-73, SCOPE. Swedish Natural Science Research Council, Stockholm. 

The global biogeochemical cycle of P is almost open. This differentiates phosphorus from carbon and nitrogen, whose natural biogeochemical cycles are, on the contrary, almost closed. 

Given all these uncertainties, it is not currently possible to determine whether the nitrogen and/or phosphorus cycles are in a steady state. Indeed, anthropogenic inputs of both are now so large that the maintenance of a steady state seems unlikely. As noted earlier, natural deviations from a steady state in the nitrogen cycle are also deemed likely given the large spatial separation between the locales where denitrification and BNF take place. 

Auclair, J. C. 1995. Implications of increased UV-B induced photoreduction Iron(II) enrichment stimulated picocyanobacterial growth and the microbial food web in clear-water acidic Canadian Shield lakes. Canadian Journal of Fisheries and Aquatic Sciences 52 1782—1788. Auclair, J. C., P. Brassard, and P. Couture. 1985. Total dissolved phosphorus Effects of two molecular weight fractions on phosphorus cycling in natural phytoplankton communities. Water Research 19 1447—1453. 

Let us now determine the functional and dynamic characteristics of the fluxes of phosphorus (Table 4.4) based on analysis of existing ideas about their nature. The atmospheric cycle is governed by rock weathering, volcanic eruptions, and by the leaching of phosphorus by precipitation. From available estimates, the content of phosphorus in the lithosphere constitutes 0.093%, and the processes of weathering deliver annually to the atmosphere from 0.67 mgPcm 3 yr 1 to 5.06mgPcm-3 yr-1. Every year, volcanic eruptions contribute to the atmosphere about 0.2 106 tP. Since these processes are complicated and stochastic in nature and their models are absent, as a first approximation fluxes H and //f9 can be considered constant. 

Krapivin V.F. (2000d). Simulation model of biogeochemical cycle of phosphorus in the biosphere. Problems of Environment and Natural Resources, 10, 26 - 30 [in Russian]. 

Devai I, Felfoldy L, Wittner I, et al. 1988. Detection of phosphine New aspects of the phosphorus cycle in the hydrosphere. Nature 333 343-345. 

The Atmosphere. - The Hydrosphere. - Chemical Oceanography. - Chemical Aspects of Soil. - The Oxygen Cycle. - The Sulfur Cycle. - The Phosphorus Cycle. - Metal Cycles and Biological Methyla-tion. - Natural Organohalogen Compounds. -Subject Index. 

Elmsley, J. (1980). The phosphorus cycle. In The Handbook of Environmental Chemistry, Vol. 1, Part A. The Natural Environment and the Biogeochemical Cycles, ed. 

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