ACCUMULATION AND TOXIC EFFECTS OF CU2-, NI2+ AND MOO42- AND THEIR ASSOCIATIONS - INFLUENCE ON RESPIRATORY RATE AND CHLOROPHYLL (A)UNDER-BARCONTENT OF THE GREEN-ALGA SCENEDESMUS-QUADRICAUDA(, CU+, MN2+, VO43)

The ecotoxicological effects expressed as respiratory rate, chlorophyl l a content and bioaccumulation of six ions (Cu2+, Cu+, MoO42-, Mn2+, VO43-, Ni2+) and their associations by the freshwater, alga Scenedesmu s quadricauda were determined. With all tested ions except MnO42- the respiratory rate was significantly or highly significantly increased i n comparison with control. With ion-ion associations, the enhancement effect of Ni2+ + Cu2+ and Ni2+ + Cu+ and the absence of effect of MoO4 2- + Mn2+ in comparison with control was confirmed. All the other test ed associations of ions decreased the respiratory rate significantly, when compared with control and with the individual effect of each test ed ion. Each tested ion decreased the content of chlorophyll a signifi cantly (p < 0.01) compared with control, while the ion-ion association s either decreased or increased it or else had no effect at all. When supplied individually, the ions taken up in greater amounts (compared to the initial content of the bathing medium) were Ni2+ (20 %), Cu2+ ( 17.6 %) and Mn2+ (15.19 %); most other ions were accumulated in amount s less than 5.5 % and the lowest accumulation was observed with MoO42- (< 0.2 %). With ion-ion associations Ni2+ and VO43- increased Cu2+ an d Cu+ accumulation, Cu+ increased VO43- and Mn2+ accumulation, Cu2+ in creased Mn2+ accumulation and Mn2+ increased VO43- accumulation. The a ccumulation of MoO42- was unaffected by any of the other ions under co nsideration while MoO42- had no effect on Mn2+ accumulation.