Biogenic silica (BSi), particulate organic carbon (POC) and nitrogen (PON) and chlorophyll α (Chl α) of surface waters were measured in the Bering Sea basin from January through March 1993. BSi concentration varied extraordinarily among stations (0.01-0.59μM) and was relatively high in the central region. POC and PON concentrations showed variations of several fold among stations (2.28-11.38μM for POC and 0.36-2.11μM for PON), and were relatively high in the eastern region. The regional variations of POC and PON concentrations reflected that of Chl α concentration, whereas the same results were not found for the BSi concentration. Extraordinary variation was found in the BSi/POC atomic ratio (0.070) were observed in the central region. Values higher than 0.13,the typical atomic ratio of cellular silicon to cellular carbon for culture diatoms, were also found. In contrast, POC/PON atomic ratios were roughly uniform (mostly 4-10) and the average was 6. 7. The present results show a possibility that diatoms with high silicon demand occur in the Bering Sea basin in winter. In addition, I also compared the characteristics of biogenic particulate matter with those in the summertime Bering Sea basin and in the wintertime Antarctic Ocean
