P/C ratio

Chemical name N-methyl-4-piperidinyl a-cyclopentylphenylglycolate MEDsn 1 -2 mcg/kg IDsn 3.4 mcg/kg LDsn 350 mcg/kg D5016-24 hr C/P ratio-2.0... 

Chemical name N-methyl-4-piperidynyl a-propynyl-cyclopentylglycolate MEDsq- 12 mcg/kg ID50 29 mcg/kg LD50 2,000 mcg/kg D50 20-28 hr C/P ratio 0.8... 

Chemical name f1-methyl-1,2,3,6-tetrahydro -pyriidinyl) methyl a-isopropylmandelatel MED504.O mcg/kg ID50 8.9 mcg/kg LD50 500 mcg/kg D5016-24 hr C/P ratio 1.6... 

C from Furnas et al. (1976) for phytoplankton production and from the organic P reported by Nixon (1981) for rivers and sewage using a C P ratio of 106 1 by atoms. Total N and P inputs from Nixon (1981). Sewage includes urban runoff. Metals from rivers and sewage measured by Hunt (unpublished report). Cu in rivers also includes data for small rivers and smaller sewage treatment plants reported by Hoffman and Quinn (1989). Metals from atmosphere estimated from data for nearby areas summarized by Nixon and Lee (in press). Hydrocarbons from Hoffman and Quinn (1989), and E. Hoffman (pers. comm, as reported in Santschi et al. in press) include Mt Hope Bay inputs and area. 

Mineral nutrient limitation of microbial degradation has been put forward as an explanation for accumulation of carbon-rich DOM after a Phae-ocystis bloom (Thingstad and Billen 1994). The increase in carbohydrate/POC due to overflow metabolism will give rise to a substrate with a C/P and C/N ratio that is unfavorable to bacteria. Since the C/P ratio of bacteria may be considerably lower than that of phytoplankton (Vadstein et al. 1988), especially phosphate limitation may hamper microbial degradation (Thingstad et al. 

If this is an adequate description of the real low-latitude ocean, then the strength of its biological pump (the amplitude of the surface-deep gradient in inorganic carbon concentration) is controlled solely by (i) the carbon/nutrient ratio of the organic matter, and (ii) the nutrient content of the deep ocean (see Equation (5)). If the C/P ratio of export production increased or the [PO4 ] of the deep ocean increased, then biological production at the surface would drive an increase in the downward flux of carbon that is not at first matched by any change in the upward flux of carbon dioxide associated with surface-deep... 

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