Nishioka, J. Central Research Institute of Electric Power Industry, nishioka@ios.bc.ca , nishioka@criepi.denken.o
Takeda, S. Central Research Institute of Electric Power Industry, s-takeda@criepi.denken.or.jp
Wong, C. S. Institute of Ocean Sciences, wongc@dfo-mpo.gc.ca

 
CHANGE IN THE CONCENTRATIONS OF IRON IN DIFFERENT SIZE FRACTIONS DURING A PHYTOPLANKTON BLOOM IN CONTROL ECOSYSTEM ENCLOSURES
 
To observe micro-nutrient and carbon dynamics in plankton ecosystems, controlled ecosystem enclosure (CEE) experiments were conducted in Saanich inlet, B.C., Canada. Two CEE (2.5m in diameter, 16m in length) were launched for the period 22 July to 5 August 1996 and enriched with 10 uM nitrate and 5.2 nM iron on day 1. Integrated depth sampling of intervals 0-4, 4-8 and 8-12m were performed on days 0, 1, 2, 3, 4, 5, 7, 9, 11 and 14. Fe concentrations were measured for five size fractions; > 20-30 um particle, 2-20 um particle, 0.2-2 um particle, 0.2 um-200 kDa small colloidal-particles and < 200 kDa dissolved species. The sediment in the enclosure was collected on every sampling day after day 2 and its iron was also determined. Size-fractionated particulate organic carbon and total Chlorophyll-a were also analyzed. The Small colloidal-particle Fe fraction decreased most significantly during a phytoplankton bloom. The rate of decrease amounts of Fe in small-colloidal particles was larger than that of total Fe, from day 1 to day 4. In contrast, the > 20-30 um Fe particles increased over the same period. The results suggest that Fe in small colloidal-particles changed to > 20-30 um Fe particles during phytoplankton growth. A large amount of Fe was kept in surface layer with phytoplankton, and transported to deep layer by phytoplankton sedimentation, proceeding the bloom.
 
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
 
Code: SS51TH0119S