Based on the above, the appropriate integrated environmental management scheme will be proposed in order to improve water quality in the Black Sea and safeguard the survival of the endangered ecosystems.
Exploitation of polymetallic sulphide, radioactive and phosphate ores has been associated with severe and widespread environmental degradation for the following reasons : mining and processing of these ores inevitable result in the creation of millions of tonnes of wastes (containing high residual concentration of toxic elements : Cu, Pb, Zn, As, Cd, Hg, nuclides) that, at least in the past, have been deposited without any precaution on the land (terrestrial deposition) or, in many cases, into the sea (marine deposition). Under physical (wind) or chemical (leaching) mechanisms, the toxic elements are mobilized and migrate to the surrounding, causing severe and widespread contamination of soils, ground, surface and marine waters.The extensive underground mining works, which remain active for tens of even hundreds of years after closure, are also a continuous source of acid mine drainage loaded with toxic elements causing severe terrestrial and sea water pollution. All sources (mining works, tailings deposits) remain active for tens or even hundred of years after minng closure.
Three areas on the Black Sea will be used as case studies :
(i) the Vromos Bay (BG) where 8mt of copper flotation tailings containing residual heavy metals and radioactive elements have been deposited on the sea shore and furthermore, mining and processing wastes deposited terrestrially are releasing acid waters heavily contaminated that pollute the surrounding soils and eventually reach the sea.
(ii) The Mouth of the Danube River (RO) where flotation tailings of a polymetallic sulphide mine generating acidic waters pollute the Danube River, eventually ending up in the Black Sea.
(iii) The phosphate plant near Constanta (RO) where millions of phosphogypsum are deposited in terrestrial dumps close to the sea causing severe contamination from the leachates containing phosphoric acid a,d radioactive elements and large quantities of waste water that are rejected into the Danube river with minimal treatment.
The methodology will involve a complete environmental characterisation of the tailings, which will include : systematic sampling of the tailings, the surrounding soils, surface and underground waters, marine bottom sludge sediments and sea water, a complete chemical and mineralogical characterization, standard EPA Toxicity Characterization Test and heavy metals speciation with the 5-stage sequential extraction technique as well as determination of the net acid generation potential. Finally, the main mechanisms responsible for the mobilization of toxic elements and the main transportation routes will be determined and the total impact on the Black Sea will be assessed.
Based on the above, technologies for environmental rehabilitation will be developed as follows:
(i) preventive technologies including containment of wastes with modified soil covers, modification of acid generating capacity with alkaline additives, relocation of most hazardous materials in engineered containment structures, etc.
(ii) remedial technologies including methods to restore the quality of the polluted soil and sea bottom by physical or chemical methods.
Funding SchemeCSC - Cost-sharing contracts
TN23 1PP Ashford