Helios Rybicka E.’s scientific contributions

The saturated with the metal ions (Cu, Pb, Cd, Zn, Tl, Ag, Hg) clay minerals were treated by aqueous H 2 S solution under controlled Eh and pH conditions. The heavy metals ions were released and precipitated at 80 o C as sulphides, in most cases appeared to be crystalline. They often form coatings or crystals overgrown on clay minerals or form tight intergroths with clay particles. After 5 days the well crystallised sulphides are formed; covellite-CuS, galena-PbS and sphalerite ZnS were identified by X-ray method. The microscope observations revealed some other Cu-Fe-minerals like chalcopyrite-CuFeS 2 , idaite, bornite. The native copper and pyrite were also observed. Cadmium formed hawleyite-CdS, whereas the crystals of greenockite were rarely found in the reaction products. Mercury react very quickly with S 2-ions and in the heavy fraction of reaction product the metacinnabar-HgS has been determined. The numbers of thallium sulphides were obtained: TlS, Tl 2 S-carlinite, Tl

In Poland the sources of metals in the rivers are Cu- and Zn-Pb mining and smelting, in Lower and Upper Silesia respectively and chemical industry. Extensive study on metal content in the Oder River showed that the most notable concentrations of Cd, Zn, Pb, Cu in sediments were found. In Germany: the Danube, Rhine, Ems, Weser and Elbe Rivers are mostly polluted with Cd, Hg, Pb and Zn. Concentration of all these metals is the highest in the Elbe River sediments in region with a very long history of mining. The considerable metal pollution (mainly Cd) enters the Elbe via the Mulde River, which accumulates the residues from mining and Cd- batteries industries. The Danube River flows through nine countries with industry representing the most significant source of river-borne pollution flowing into the Black Sea; high metal concentration in the Danube sediments suggests their source from mining.

Chemical speciations of heavy metals in different type of Sea depandes very strongly on the sea water salinity and on type of sediments. Very important was the mineralogical compositions - concentration and types of minerals. Clay minerals are the most important consudering the sorption and desorption capacity of heavy metals.

The sulfides characteristic of unoxic sediments show partly very low temperature stability. Basing on this low stability, an attempt has been made to synthetize sulfide minerals in the water medium through the solid phase solutions by means of thermostate. The following sulfides were crystallized: CuS - Covellite, PbS - Galena, CdS Hawleyite, Metacinnabar HgS. As the initial materia for experiments the following clay minerals were used: Kaolinite, Illite and Smectite - for all their size fraction <2um.

During the last 100-150 years, a conciderable increase of heavy metals conc. in the river sediments has been observed. The highest metal conc. in the river sediments was foun for Cd, Pb. Cu, and Zn. maximum conc. for the metals were (mg/kg) 500 for Cd, 3500 for Pb, 750 for Cu and 34900 for Zn, respectively. From all studied metals, Cd and Zn seems to be of particular concern because of the high level that appears to be bioavailable, and their high mobility. The exchangeable and carbonatic chemical forms of Cd and Zn reached for each up to 50% of their total amount.