Hidrológiai Közlöny 1991 (71. évfolyam)

6. szám - Hegedűs János: Rapid alga-teszt alkalmazása felszíni vizek akut mérgezőképességének kimutatására

354 HIDROLÓGIAI KÖZLÖNY 1991. 71. ÉVF., fi. SZAM at 22 + 1 °C for 22 hours under 4000 lux uniform illumination. The oxygen produced by the algae during tlie incubation period displaces somé of the liquid from the Durham tűbe and is collected in the upper part. For reading, tlie Durham tubes are placed on a laboratory level, so that the gas bubble forms a sphere at the center of the Durham tube. The radius of the sphere is measured and the volume of the sphere calculated. The toxic content and toxic potential of the sample is indicated by the impeded photosynthetic activity, tlie reduced quantity of oxygen relatíve to the reference sample. The samples were evaluated in terms of the percentages relatíve to the reference samples as follows: 100.0—90.0% — non toxic 89.9%—60.0% —slightly toxic 59.9—30.0% — moderately toxic 29.9—10.0% — strongly toxic 9.9— 0.0% — highly toxic. The test results imply alsó the limit of nieau tolerance, TL

m. Tlie method is illustrated by the tests performed on four minor tributaries of the Danube, the Rákos Creek (left-hand, R. St. 1652 km), the Hosszúrét Creek (riglit liand, R. St. 1638 km), tbc uncontrolled discharges on the right-hand bank at R. Sts. 1649 and 1629 km. The two creeks were found to carry considerable faecal pollution and toxic substances and can no more be considered as natural streams. The elevated quantity of continuously present toxic substances in the uncontrolled discharges areagrave hazard to tlie quality of Danube water. Keyworils: HEGEDŰS JÁNOS Szakmai munkásságának összefoglalóját a Hidrológiai Közlöny 1989. évi 5. számának 293. oldalán közöltük. Toxicity, algae rapid test, discharges, Danube