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Particulate silica and Si recycling in the surface waters of the Eastern Equatorial Pacific

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningfagfællebedømt

  • Mohamed Adjou
  • Paul Tréguer
  • Cynthia Dumousseaud
  • Rudolph Corvaisier
  • Mark A. Brzezinski
  • David M. Nelson
The distributions of biogenic and lithogenic silica concentrations and net silica production rates in the upper 120 m of the Eastern Equatorial Pacific (EEP) were examined in December 2004, on two transects situated at 110°W (4°N to 3°S) and along the equator (110°W to 140°W). Lithogenic silica (lSiO2) was generally <10 nmol Si l-1 with maximum concentrations reaching 25 nmol l-1 in surface waters. These low concentrations confirm low atmospheric inputs of particulate Si, consistent with reported low inputs of wind-borne material in the EEP. In spite of active upwelling of silicic acid-rich waters the biogenic silica (bSiO2) concentrations were generally low, falling between 100 and 180 nmol Si l-1 in the upper 50 m and decreasing to less than 50 nmol Si l-1 below ~90 m. Estimates of net bSiO2 production rates revealed that the rate of production exceeded that of dissolution in the upper euphotic layer (0-40 m) along 110°W with net production extending somewhat deeper (60-100 m) to the west along the equator. Net production rates in the surface layer were low, ranging between 5 and 40 nmol Si l-1 d-1, consistent with previous observations that diatoms are small contributors to autotrophic biomass in the EEP. Net silica dissolution predominated in the lower euphotic layer (40-120 m), indicating active Si recycling which diminished the strength of the silica pump in this region.

OriginalsprogEngelsk
TidsskriftDeep Sea Research - Part II - Topical Studies in Oceanography
Vol/bind58
Udgave nummer3-4
Sider (fra-til)449-461
Antal sider13
ISSN0967-0645
DOI
StatusUdgivet - 2011

ID: 40323081