Trace Element Uptake Assessment in the Planktonic Biofiltration System

Resumo

The concentration of trace elements (Fe, Mn, Cr, Co, Ni, Cu, Pb, Cd, and As) through the planktonic food chain of the White Sea have been studied with an experimental approach. The zooplankton sampled in the reference area fed on seston containing different concentrations of trace metals. Seston sampled at the Chupa station was enriched in Fe, Cu, Pb, Cr, Co, As, and Ni compared to seston sampled at Kartesh station (reference area). The differences in concentrations of the suspended particular matter and of elements indicating a terrigenous admixture (Al, Ti, Zr) are evidence of a higher natural background of trace metal content in seston from Chupa due to the higher contribution of the mineral component. Zooplankton that fed on seston characterized by a higher trace element content accumulated Fe, Mn, and Cr, and to a lesser degree, Ni, Co, Pb, and Cu; in particular, these were the elements with a high content in seston. Despite the absence of significant differences in the Mn content in the two groups of seston, its apparent accumulation by zooplankton and reduced content in fecal pellets are evidence of the highest digestibility of Mn by zooplankton, which can be associated with the bioavailability of Mn in the food source. When the content of trace metals in pellets and seston are compared, the fecal pellets of zooplankton are depleted in major elements, and their contents are (% of content in seston): Zn, 72%; Mn, 24; Cu, 97; Pb, 62; Cr, 99; Co, 78; Ni, 87; As, 96; and Cd, 65%.