In this paper a part of results of the wastewater quality control from the Thermal Power Plant "Kostolac", water from the rivers Danube and Mlava, and groudwaters near by (Serbia, Yugoslavia), is considered. In order to protect environment from the effects of hurtful substances make during working process of Thermal Power Plant "Kostolac" is especially does using solid fuel (coal), the Institute of Public Health of Serbia following an approved program checks upon the quality of groundwaters, water the rivers Danube and Mlava including the wastewater from the Thermal Power Plant "Kostolac", four times a year. The results of our research point out to the hurtful effects of the wastewater from Thermal Power Plant "Kostolac" on the groundwater.

In this work, we were investigated level and source of trace elements in industrial and sea waters in Bokakotorska Bay (Adriatic sea, Montenegro, Yugoslavia). The ranges concentration in (microgram/cubic dm) in seawater are as follows: Hg (0.1-0.4); As (0.1-0.9); Pb (2.3-10.0); Zn (3.0-12.0); Cu (2.3-8.4); Cr (0.8-3.0); Cd (0.1-1.0); Ni (0.9-3.0); Mn (0.2-0.5). The average levels of trace elements in the samples collected from industrial effluents of factory ILK were 110 - 16500 times higher than concentrations of trace elements in other industrial effluents.

To evaluate precision and reliability of recently introduced Metal Pollution Index as a method for metal pollution monitoring of surface waters, a series of toxicity tests with Daphnia magna have been undertaken. The sampling sites (the River Danube wetlands and Hydrosystem DTD (Danube - Tisza - Danube), Serbia, Yugoslavia) for this study have been chosen according to previously recorded high MPI values. Chemical characterization and WET (whole effluent toxicity) testing of selected waste waters at the chosen sampling sites, and the recipient water toxicity testing upstream and downstream the discharger evaluated the validity of MPI, and, on the other hand, discriminated the effects of background pollution. The results of acute and chronic toxicity tests of water and sediment corresponded well with MPI values, which leads to a conclusion that MPI could be regarded as a reliable and precise method for metal pollution monitoring of surface waters.