V. Atanasov, E. Valkova, G. Kostadinova, G. Petkov, Ts. Yablanski, P. Valkova, D. Dermendjieva
Abstract. A survey and assessment of manganese (Mn) levels was carried out on the chain water – sediment – algae from 6 monitoring points, situated at three rivers and a dam with high anthropogenic impact in Stara Zagora region, South Bulgaria. International references of ISO and BSS for sampling and sample preparation of water, sediment and algae analysis were used. Manganese concentration in the collected samples was determined by atomic absorption spectrometry (AAS). It was found that despite the anthropogenic pressures on the studied waterbodies Mn content in water from all investigated waterbodies does not exceed the maximum permissible concentration, according to national Regulation No 7/1986. Mn accumulates in high levels in sediment and algae from all surveyed monitored waterbodies. The highest Mn concentrations in sediment were measured in Sazliyska River (714.5 mg/kg) and Bedechka River (799.6 mg/kg). With the highest levels of Mn were distinguished algae delivered by Yagoda Village (663.8 mg/kg), Jrebchevo Dam (476.0 mg/kg) and Sazliyka River (411, 5 mg/kg). The estimated ratios between Mn concentrations in sediment and water have shown that the accumulation of this metal in the sediment is from 1407 (Jrebchevo Dam) to 15466 (Tundzha River, Banya Village) times more than in the water. By the sediment/algae ratio it is found that Mn is accumulated from 0.5 (Jrebchevo Dam) to 2.4 times (Bedechka River) more in sediment compared to algae. The data from algae/water ratio show that Mn is accumulated from 1301 (Tundzha River at Jrebchevo Dam) to 19565 (Tundzha River at Banya Village) times more in the algae compared to the water. This fact suggests the mechanism of accumulation of Mn in the sediment and algae, probably different from simple diffusion. The obtained results indicate that sedimentand algae can serve as good indicators of pollution by Mn. They can also be used for purification of water from that metal.