Influence of nitrate on metal sorption and bioaccumulation in marine phytoplankton, Dunaliella salina

Coastal organisms are often exposed to both metal pollution and macronutrient enrichment. Dunaliella salina, a uni-cell, cell-wall-less green marine microalga, was used as a model marine organism. The influences of major nutrients additions on the absorption (intracellular uptake), adsorption (cellular surface uptake), and bioconcentration of trace metals (Fe, Mn, Zn, and Cu) in Dunaliella salina over 10 days were examined. When N:P ratio was 16 (8, 0.5 mu mol/L for nitrate, phosphate), both metal absorption and bioconcentration factor were the most. The maximum and minimum metal adsorptions were obtained, respectively, at N:P ratio of 110 (55, 0.5 mu mollL for nitrate, phosphate) and 25 (12.5, 0.5 mu mollL for nitrate, phosphate). The difference in ambient nitrate concentration did not affect the order of metal adsorption of Dunaliella salina (Fe >> Zn > Mn > Cu), but the absolute adsorption quantities were greatly affected. The influence of nitrate concentration on metal absorption and adsorption was different. (C) 2007 Wiley Periodicals, Inc