Phosphorus

About: Phosphorus is a research topic. Over the lifetime, 53120 publications have been published within this topic receiving 939731 citations. The topic is also known as: element 15 & P.

Two-dimensional crystals: Phosphorus joins the family

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A Method to Determine a Phosphorus Adsorption Maximum of Soils as Measured by the Langmuir Isotherm

Abstract: Adsorption of phosphorus by soils from dilute solutions showed a closer agreement with the Langmuir isotherm than with the Freundlich isotherm. Constants calculated from the Langmuir isotherm and interpretations based upon the meaning of these constants permit a sound theoretical approach to some of the problems of phosphorus retention in soils. The adsorption maximum claculated from the Langmuir isotherm was closely correlated with the surface area of soils as measured by ethylene glycol retention. The correlation coefficients and regression equations were r = 0.98 and y = 0.276x + 3.47 for 10 alkaline soils, and r = 0.96 and y = 0.641x + 5.73 for 12 acid soils, where y = mg. P per 100 g. soil and x = mg. ethylene glycol retained per g. of soil. For a given surface area, i.e., 30 mg. glycol per g. soil, the acid soils held 2.17 times as much phosphorus as the alkaline soils. The average values of a second constant, k, derived from the slope and intercept values, were 0.92 and 4.39 for the alkaline and acid soils, respectively. As the value of this constant increases, the bonding energy of the soil for phosphorus increases. Thus, the acid soils retained more phosphorus per unit of surface area and also held the phosphorus with a greater bonding energy than the alkaline soils

The marine phosphorus cycle

Abstract: Phosphorus introduced to the ocean must ultimately be removed if a steady state is to be maintained over geologic time. Aeolian input is insignificant, and there is evidently no hydrothermal contribution. Rivers dominate P-input to the ocean. The fluvial P-flux is poorly quantified due to the interactions of two factors: (1) man's influence on river-nutrient fluxes; and (2) inherent complexities in understanding the biological and inorganic associations of P in estuarine and coastal waters. Our best estimate of the natural or pre-man P-input flux is about 10 x 10/sup -9/ moles - P/cm/sup 2/-ocean surface/year. Of the identified flux of phosphorus to the sediments, about 90 percent is in the form of biogenic debris or its regeneration products. The burial of phosphatic fish debris is negligible. P-removal by direct reaction of phosphate in seawater with sea-floor basalts during mid-ocean ridge hydrothermal circulation is insignificant. P-removal by processes such as sorption on clay surfaces or formation of authigenic Fe and Al phosphate phases is presently unquantified and remains a serious uncertainty in the phosphorus cycle. The identified sources and sinks approximately balance, yielding a residence time for P in the oceans of about 10/sup 5/ yrs.

A comparative analysis of nutrients and other factors influencing estuarine phytoplankton production

Abstract: We reviewed data concerning phytoplankton production, chlorophyll a, and associated physical and chemical variables from 63 different estuarine systems. Data were analyzed statistically to test hypotheses regarding algal productivity and factors regulating temporal patterns. Prior to statistical analysis, estuarine systems were classified into four groups based on criteria of physical circulation and geomorphology. Analysis of grouped data indicated that algal production and biomass were consistently high in warm periods of the year in a broad spectrum of estuaries and that ratios of available nitrogen to phosphorus were low during periods of high production, except in highly eutrophic systems. In general, phytoplankton production and biomass exhibited weak correlations with a variety of physical and chemical state variables, perhaps indicating the significance of rate processes as opposed to standing stocks in regulating these important features of estuarine systems. A six-year time series of measurements of algal production and chlorophyll a at stations in middle Chesapeake Bay exhibited considerable year-to-year variability, with a three-fold range in peak values. Summertime maxima were strongly related to annual loadings of both nitrogen (N) and phosphorus (P) but annual production appeared to be sustained primarily on recycled nitrogen and phosphorus. To generalize from these findings, N and P loading rates were estimated for 14 different estuarine systems, and a significant positive relationship was obtained between phytoplankton production and nitrogen (but not phosphorus) inputs.