Lampman, G. Institute of Ecosystem Studies, lampmang@ecostudies.org
Caraco, N. Institute of Ecosystem Studies, caracon@ecostudies.org
Cole, J. Institute of Ecosystem Studies, colej@ecostudies.org

 
A METHOD FOR MEASUREMENT OF PARTICUALTE C AND P ON THE SAME FILTERED SAMPLE
 
Because C:P ratios may influence food quality of phytoplankton to zooplankton grazers, there is substantial interest in measuring C:P ratios in aquatic systems. In most analyses C is measured by dry combustion using a C-N analyzer. This requires that P be measured on a separate sample. Here we show that C can be measured by a variation of the same wet digestion method (Persulfate) frequently used for P analysis and, therefore, C and P can be measured on the same filter. Over a large range of C values (1-40 uM/filter), the persulfate method for measuring C gave the same C value on seston and phytoplankton as did dry combustion on a Carlo-Erba CN analyzer. The method is also cheaper than the dry combustion method of measuring C both in terms of equipment and per sample materials costs. Further, the persulfate method is more precise (cv=3%) as compared to the dry combustion method (cv=12%) for the measurement of C. This greater precision of C measurement, and the fact that C and P are measured on the same sample, means that small differences in C:P ratios can be more readily detected.
 
Day: Tuesday, Feb. 2
Time: Poster
Location: Sweeney Center
 
Code: SS49TU0095S