BIOLOGICAL EFFECTS OF TRIAZINE HERBICIDE CONTAMINATION ON MARINE-PHYTOPLANKTON

The effects of the herbicide atrazine on marine phytoplankton typical of the German Eight (North Sea) were investigated by means of four mes ocosm (tank) experiments. Three tanks were spiked with atrazine (120, 560, and 5,800 ng/L, respectively). These concentrations cover the ran ge found in the German Eight, in coastal waters, and in the estuary of the river Elbe. The lowest atrazine concentration applied was of the same order of magnitude as the background concentration of triazine he rbicides in North Sea water near the island of Heligoland. A relations hip between concentration of atrazine (dosis) and concentration of ''e xcreted'' dissolved organic phosphorus (DOP) as well as dissolved orga nic nitrogen (DON) (effect) can be inferred, where high concentrations of triazines lead to high concentrations of DON and DOP. Furthermore, the decrease in the pH-value from 9.2 to about 8.7-8.9 in the three t anks spiked with atrazine during the ''stationary growth phase'' in co mparison with the fourth tank (control, i.e., background levels) impli es that photosynthesis is reduced. This effect is accompanied by lower chlorophyll concentrations, reduced primary production, and higher co ncentrations of amino acids in the water.