COASTAL COLLOIDAL CARBON - STUDY OF ITS SEASONAL-VARIATION AND THE POSSIBILITY OF RIVER INPUT

The concentration of organic colloidal and non-particulate carbon was monitored for one year off the coast of North Carolina. The mean value for colloidal carbon was 148 ± 25.0 μg 1-1. No seasonal pattern was apparent. Furthermore, the amount of colloidal carbon appeared to be independent of the amount of non-particulate carbon. On an average, 11 ± 2.0% of the nonparticulate carbon was colloidal. A strong negative correlation between colloidal carbon concentrations and salinity was found, indicating that the bulk of the colloidal material in rivers does not reach the coast. 'Fingerprints' obtained with pyrolysis-gas liquid chromatography show that coastal and river/estuarine colloidal material are composed of different compounds. Coastal colloidal material had no significant fluorescence or light absorption in the u.v. and visible range, indicating that it is poor in aromatics and other chromophores. Therefore, it is not composed of gelbstoff. © 1979.