Distribution and determination of Pb, Cd, Bi and Cu in the sea brine system: solution--colloidal particles--biota

The distribution of Pb, Cd, Bi, and Cu in Black Sea brine system (solution--colloidal particles--biota) produced in Burgas and Pomorie salterns is studied. The established distribution of the title elements among the brine components is as follows: Pb--25% in the salt solution, 30%--in colloidal particles, 45%--in biota (Halobacterium salinarium and microalgae Dunaliela salina); Cu--30% in the salt solution, 22%--in colloidal particles, 48%--in biota. Cd and Bi are not detected in biota. They are uniformly distributed (50%: 50%) between the salt solution and colloidal particles. Two procedures for analysis are developed. The first one is designed for determination of the total content of the studied metals in brine. It involves elimination of the biota interference by addition of ethanol, extraction and pre-concentration of the metals with NaDDC into CCl4 followed by FAAS determination. The second procedure intends determination of the elements in the separate components of the brine. It involves separation of the colloidal particles through centrifugation, separation of the studied elements from the resulting solution as dithiocarbamate complexes on a Millipore filter, dissolution of the retained metal species and subsequent FAAS analysis.