C:N:P ratios

The wastewater field has more than 100 years of treating difficult waste materials in an aqueous environment. There are sophisticated models for wastewater treatment which can be applied to the remediation field, and the methods and the approaches are also useful. The introduction of a C N P ratio or the introduction of various simple operating parameters has been cost effective, and may be applicable in the remediation field as well. From some of the new reactor designs and applications, it appears that some remediation problems may be those which have already been studied by the wastewater field, and that there are lessons to be learned as well as new and innovative approaches still remaining to be evaluated. 

A simplified conceptualization of oceanic DOM pools based on a two-pool model showing carbon concentrations and elemental C N P ratios of the DOM pools. In reality, the reactivity of DOM probably spans a continuum that is presented herein as two pools, labile and refractory, for the purposes of simplification. Molar elemental ratios are in the format of C N P. Source-. From Hopkinson, C. S., and J. J. Vallino (2005). Nature 433, 142-145. 

Based on the successful laboratory soil microcosm experiment, the most heavily contaminated soil was excavated from the surface (2 m) layerand treated ex situ. The soil was placed in an enclosed rectangular bed and its moisture content maintained at 15% (w/w). The soil was aerated with an agricultural spading machine. Surfactant, organic nutrients, and inorganic nutrients were applied to maintain an optimum C N P ratio (data not presented). The isolated microorganisms were inoculated into the soil as dilute suspensions on five separate occasions. 

Cimbleris, A. C. P., and J. Kalff. 1998. Planktonic bacterial respiration as a function of C N P ratios across temperate lakes. Hydrobiologia 384 89—100. 

Melillo, 1985). The accumulation of excess carbon on the sea floor acts as a minor sink today for fossil fuel and land use carbon. The magnitude of this sink is controversial (Table 9.1) but may represent as much as 10% of the yearly carbon storage in the atmosphere. The accumulation of 30 x 10 2 moles C as organic matter yearly would represent 4.5 x 1012 moles N and 0.3 x 1012 moles P at a C N P ratio of 106 16 1. 

Of the organic carbon entering the ocean, about 35% accumulated in marine sediments as organic carbon with a molar C/N/P ratio of about 250/20/1 (Mackenzie, 1981) the rest was respired and oxidized to CO2 and evaded the ocean. The nitrogen and phosphorus riverine fluxes of 1 and 0.045 x 1012 moles y1, respectively, represented the nutrient fluxes necessary to support the organic matter accumulation of 11.7 x 1012 moles C y1. 

Frost, P. C., Stelzer, R. S., Lamberti, G. A. Elser, J. J. (2002). Ecological stoichiometry of trophic interactions in the benthos understanding the role of C N P ratios in lentic and lotic habitats. Journal of the North American Benthological Society, 21,515-28. 

Ruttenberg, K. C., and M. A. Goni. 1997. "Phosphorus distribution, (C N P) ratios, and delta 13C in arctic, temperate, and tropical coastal sediments tools for characterizing bulk sedimentary organic matter." Marine Geology 139, 123-145. 

Fourqurean, J. W., Zieman, J. C., and Powell, G. V. N. (1992). Phosphorus limitation of primary production in Florida bay Evidence from C N P ratios of the dominant seagrass Thalassia testudi-num. Limnol. Oceanogr. 37, 162—171. 

Tezuka, Y. (1989). The C N P ratio of phytoplankton determines the relative amounts of dissolved inorganic nitrogen and phosphorus released during aerobic decomposition. Hydrobiologia 173, 55-62. 

Touratier, F., Field, J. G., and Moloney, C. L. (2001). A stoichiometric model relating growth substrate quality (C N P ratios) to N P ratios in the products ofheterotrophic release and excretion. Ecol. Model. 139, 265-291. 

One feature that has great relevance to the importance of DOM to the carbon cycle is its enrichment in carbon over the Redfield proportion. The C N P ratios of high molecular weight DOM are on the order of 350 20 1 (Kolowith et ai,... 

Inputs of agricultural fertilizers are having more than one impact on the biological pump. A shift in the NO PO4 Si(OH)4 of natural waters is causing a shift in the phytoplankton community structure that should impact the biological cycling of carbon in aquatic systems (Conley et al, 1993). Additionally, a recent shift in the C N P ratios of deeper waters and an increase in export production have been observed for the northern hemisphere oceans (Pahlow and Riebesell, 2000). 

Burkhardt S., Zondervan I., and Riebesell U. (1999) Effect of CO2 concentration on C N P ratio in marine phytoplankton a species comparison. 

A proper balance of nutrients is required for plant growth. In marine systems, the stoichiometry of primary production is determined by the ratio of elements in the cytoplasm (Redfield ratio) that supports optimal metabolism of phytoplankton (Redfield, 1958). The C N P ratio is fairly constant in marine phytoplankton, and this ratio in primary producers constrains the cycling of aU elements (Elser et al., 2000). The amount and proportions of nitrogen and phosphorus available determine the amount of carbon fixed by phytoplankton. Limitation by either of these... 

Goldman J. C. (1986) On phytoplankton growth rates and particulate C N P ratios at low light. Limnol. Oceanogr. 31, 1358-1361. 

Ruttenberg K. C. and Goni M. A. (1997b) Depth trends in phosphorus distribution and C N P ratios of organic matter in Amazon Fan sediments indices of organic matter source and burial history. In Proc. Ocean Drilling Program. Sci. Res. (eds. R. D. Flood, D. J. W. Piper, A. Klaus, and L. C. Peterson), vol. 155, pp. 505-517. 

One of the most useful findings that oceanographers have made in support of a chemical perspective on ocean processes has been that the C N P ratios of mixed marine plankton (zooplankton and ph5doplankton) collected by towing nets (>64 rmmesh) through the surface ocean occur at relatively constant values, near 106 16 1. This observation was published by Redfleld (1958) and then later elaborated by Redfleld, Ketchum, and Richards (RKR, 1963), who fleshed out the ratios in the form of an equation for photosynthesis ... 

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