Hazard classification of Danube-Delta (water and sediment) based on organisms sensitivity

Abstract

A preliminary acute evaluation of toxicity in Danube River - Danube Delta Romanian sector (1075 – 0 km) was proposed including surface-water and sediment. The conventional classification of natural waters is based primarily on chemical and physical parameters. Recently the hazard classification have include the use of selected microbiotests based on organisms sensitivity. The spatial (11 control points) and temporal (in winter and spring of 2013) toxicity effects have been assessed using a biotests battery with representative species of producers (grean algae Pseudokirchneriella subcapitata) and consumers (rotifers - Brachionus calyciflorus, crustaceeans – Daphnia magna, Heterocypris incongruent). The physical, chemical, biological and microbiological characteristics of water and sediment also have been performed. The preliminary tests results revealed no acute to slightly toxic effect, respectively Class I and II of hazard. The sediment samples were more toxic than water. The toxicity results were directly influenced by organisms sensitivity, sampling locations, season and climate change issues. The water quality according to hazard classification was related to pollution classification and biological determinations (macrozoobenthos, phytoplankton and zooplankton).