TRACE METAL POLLUTION IN WATERS FROM THE ACTIVE AND ABANDONED MASSIVE SULFIDE DEPOSITS AND WASTES AROUND GIRESUN, TURKEY

This study was undertaken to assess the status of drinking and river water quality in the urban areas in Espiye region (Giresun, Turkey), where the largest massive sulfide (VMS) deposits were formed in Turkey. This study was made at about 100-120 square km area, and waters contaminated with over 20 different ore deposits/wastes in different scale. A total of 40 water samples were collected along the main rivers and stream, spring, and leakage waters. Some in-situ parameters, such as pH, electrical conductivity, temperature, and dissolved oxygen, were also measured on-site. The filtered water samples digested by the acid digestion method were analyzed using inductively coupled plasma mass spectrometry for heavy metals and other elements.

The tectonically controlled fossil VMS deposits hosted in the Maastrichtian-Eocene magmatic rocks are either active or have been abandoned hundreds years ago. The main ore mineral assemblages are chalcopyrite, sphalerite, galena, and pyrite. The oxidation of the sulfide minerals in the deposits and wastes has caused to acid mine drainage (AMD) and the effect of AMD continues.

Most of the spring, stream and leakage waters have a strongly acidic pH and high sulfate content, and concentrations of Pb, Zn, Fe, and Cu can reach extremely high values. In addition to these elements, the concentrations of Cd, As, Mo, Se, Sb, Tl, and Bi are higher than the international and national drinking water guideline limits. Iron, aluminum, and zinc levels in stream, spring and leakage waters are enormously higher than those of the rivers. The high concentrations of toxic elements, mainly in the stream and leakage waters, are above the WHO-specified maximum acceptable level in drinking water. The risk index values of toxic elements, in the river water shows no or low risk, while most of the stream, spring and leakage waters show high and/or extremely high risk values. The concentration of the metals and pollution levels of most of the stream, spring and leakage waters may pose environmental risks and they cause disturbances brought to the living things in the area.