E. Valkova1*, V. Atanasov1, K. Velichkova2, G. Kostadinova3, M. Tzanova1 1Department of Biochemistry, Microbiology and Physics, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria 2Department of Biology and Aquaculture; Faculty of Agriculture, Trakia University, 600

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 anthro