N. Georgieva, Z. Yaneva, D. Dermendzhieva, V. Kotokova

Abstract. The aim of the present study was ecological monitoring of Cr (VI) concentrations in surface waters from Stara Zagora Region used in agriculture. The research goal was accomplished by: determining Cr (VI) concentrations in real surface water samples taken from 16 sampling points situated in four municipalities: Stara Zagora, Kazanlak, Chirpan and Gurkovo, by AAS (Atomic Absorption Spectrometry) during the period December, 2009 – November, 2010; comparative estimation of the experimental results from the standpoint of national/international surface water quality standards; statistical analyses of the data. The scientific investigations revealed that the II category standard (0.05 mg/L Cr (VI)) was exceeded by 2 % – 30 % in approximately 19 % of the samples analyzed (Tundzha River – bridge Yagoda Village, Radova River, Zetyovo Dam, Chirpan Dam). The registered Cr (VI) concentrations during November, 2010,  in 31 % of the surface water bodies practically coincided with the above cited permissible limit.