Assessment of impact of coal mining on ground and surface waters in Tozaklı coal field, Kırklareli, northeast of Thrace, Turkey

In this study, the surface and groundwaters of Tozaklı Coal field were investigated in order to determine possible environmental impacts of coal mining on water pollution. The water samples were analyzed for chemical, trace metal and microbiological quality, and compared with international directives (EPA and WHO) in order to determine the impact of the mining activities as a source of pollution on bodies of water. Tozaklı coal was lignitic rank, and sulfur content varied between 9 and 4 %. The pH values of the waters were between 8.04 and 6.92 for the mine ponds, and 8.7 and 6.6 for the groundwater and surface water. The Ca⁺², Mg⁺², Na⁺, K⁺, Cl⁻, SO ₄ ⁻² and NO₃ ⁻ values of the waters varied between 394.2 and 52, 195 and 1, 200 and 22, 6 and 1, 1 and 0.9, 756 and 20, 2.4 and 1.1 mg/l, respectively, in the mine ponds. All the major cation and anion and trace element concentrations were below admissible limits of both EPA and WHO, except for SO₄ ⁻ and NO₃ ⁻. All the mine ponds and tap waters of the villages were contaminated by Enterococcus spp., while E. coli and total coliforms were only present in the mine pond waters. The geoaccumulation index (Igeo) values of the clay samples from the mining area revealed that the soils were moderately contaminated by Ni, whereas As and Ni concentrations had high anthropogenic shares due to coal mining. The surface and groundwaters of the study area were not polluted by the coal mining operations.