Ecotoxicological Studies on the Kilian Branch and Delta of the River Danube
Amounts of priority toxicants (heavy metals, petroleum and petroleum products, surfactants, phenols, organochlorine pesticides) in water, bottom sediments, macroinvertebrates, fish, and birds of the Kilian branch and delta of the River Danube were studied from 1978 to 1985. The bottom sediments and larger organisms were shown to be highly polluted by pesticide residues and heavy metals. In the water, organochlorine pesticides were almost completely adsorbed on suspended particles, while metals were found both in solution and in the suspended phase, forming high-molecular-weight complex compounds. Accumulation coefficients for DDT in the higher links of trophic chains (i.e., predatory fish, fish-eating birds) were 105 to 106. Danube river water was found have both acute and chronic toxicity, which was confirmed by biotesting on planktonic crustaceans. Toxicity varied in time and was of a pulsed character.