Reciprocal effect of Cu, Cd, Zn on a kind of marine alga

The toxic effect of two or more trace metals which exist simultaneously in seawater on micro-organisms was studied. Seawater is a very complicated medium and the combined effect of multi-pollutants is even more complicated. Three categories of reciprocal effect exist: additive, synergism and antagonism, depending on the species distribution of the metals, algae and the comparative concentrations of each metal. For the Phaeosactylum---Cu---Zn---Cd system, antagonism occurs if Cd/Cu is in the range of 0.4 to 4, but synergism appeared beyond this concentration range; zinc and copper presented antagonism when the ratio of Zn/Cu was between 1 and 20, synergism appeared out of this range; the total toxicity was contributed by Cd when Zn was low and was controlled by Zn when Zn was high. The mechanism of such interaction was also studied.