Utilization of a multi-parameter sensor network for online monitoring of the water quality in the lignite mining area of Kozani, Greece

The present study is focused on the examination and evaluation of environmental pressures on the aquatic resources of western Macedonia region (Greece) and particularly in Kozani lignite mines area, and on the development of a water quality monitoring system in the region, in order to identify potential impacts to the adjacent water resources. A multi-parametric sensor system was installed in three representative sites of the target area and the corresponding measured parameters included pH, temperature, conductivity, nitrate ions (NO3-), sulfate ions (SO42-), and chloride ions (Cl-) for a period of about 10 months. Additionally, certain other complementary physicochemical parameters (turbidity, hardness, COD, BOD5. DO, TSS, NO4-, NH4+, Fe, and Al) were measured in selected grab samples, collected from certain points in the same area, in order to have an integrated view of water quality. The pH values ranged between 7.6 and 8.3 and remained quite stable in all three monitoring stations. Conductivity values ranged from 188 to 1,082 μS/cm; in addition, the wide NO3- content—observed only in Ag. Dimitrios Public Power Corporation Station—was attributed to the discharge of partially treated wastewater effluents. A detailed analysis of recorded measurements on a day-to-day level, especially for SO42- and Cl- values, revealed potential pollution incidents. Comparison with meteorological data of the area for the corresponding period did not show any significant correlation between measured concentrations and rainfall quantity, indicating a negligible effect of surface drainage on water quality.