Particulate Organic Carbon Flux to the Arctic Ocean Sea Floor

Abstract

Compared to other areas of the world’s ocean, polar seas have a large influence on the atmosphere’s CO2 content (Anderson et al. 1990), mainly due to deep-water formation, subduction and surface water-cooling. Sequestration of atmospheric CO2 in polar seas takes place, in part, through the action of the surface biota. One way the photosynthetically fixed carbon becomes inaccessible to the atmosphere is through gravitational sinking particulate organic carbon (POC) or vertical export with denser water of dissolved organic carbon (DOC) to intermediate depths (Fig. 5.1). The dynamics of vertical flux of biogenic matter, and to a lesser extent also the composition of exported matter has been investigated in a variety of marine ecosystems over the past two decades. Major seasonal, regional and inter-annual variations on the quantity and composition of biogenic matter exported from the upper water column have been observed. Loss of organic matter takes place mainly through settling of phytoplankton cells, detritus and zooplankton faecal pellets (Fig. 5.1). Open image in new window Fig. 5.1. Schematic illustration of principal processes during the productive cycle in the Arctic Ocean. The height of the sun and the declining and increasing snow and ice thickness are shown. The growth of ice algae in spring and autumn reduces the incident light. The spring bloom, the phytoplankton development, the vertical export and the dominance of phytoplankton cells in spring and faecal pellets from zooplankton grazing in summer and early autumn are illustrated. The depth of the euphotic zone is depicted. In addition, the transition from phytoplankton dominance in late spring to detritus dominance in autumn is illustrated. Redrawn after a figure provided by M. Fukuchi