Vertical Flux Profiles of Particulate Material in the Sea of Sanriku

Abstract

（要校正）k~ng part~culate material was collected d~~ectly uslng a particle collector- system in the sea area off Sanriku (Japan) in June 1977 and May 1978. A serles of collectors were set for a day at the depth [range of 50-500 ni along a suspension lope hung from a surface buoy system. Many par-ticles collected were v~sible to the naked eye; nilcloscopic obser\~ations revealed that more than 90 % of the par-t~cles above 125 pm In d~ameter were e~thel fresh fecal pellets of zooplankton or dislntegl-ated loose clunips of posslble fecal orlgln. These partrcles conta~ned many skeletal remalns, e. g of diatoms The maximum vertical flux of thes~nk~ng part~cles obta~ned in 1978 was 418 mg C m->d ' at 100 m. This corresponds to abo~~t one third the dally prlmdl-y product~on In thr euphotic layer above Below 100 m, the downwar-cl flux gradually drmin~slied to d level of 300 nig C nl L d-' at 250 m. A sharp decrease was found between 250 and 400 m; the pdr.t~culate fl~ix was 28 mg C m ' d-I at 500 ni Tli~s profrle 1s very d~fferent frorn the vertical variation In part~culate organrc carbon s~niultaneously observed, the lattci havlng a sharp peak at the depth of 50 m Th~s 1ndlcate5 that srnk~ng particles such as fecal pellets const~tute most of the downward flux of niatrl-~als and that the real flux of material 1s different - both In