Ecological risk assessment of cheese whey effluents along a medium-sized river in southwest Greece.

An ecological risk assessment of cheese whey effluents was applied in three critical sampling sites located in Vouraikos river (southwest Greece), while ecological classification using Water Framework Directive 2000/60/EU criteria allowed a direct comparison of toxicological and ecological data. Two invertebrates (Daphnia magna and Thamnocephalus platyurus) and the zebra fish Danio rerio were used for toxicological analyses, while the aquatic risk was calculated on the basis of the risk quotient (RQ = PEC/PNEC). Chemical classification of sites was carried out using the Nutrient Classification System, while benthic invertebrates were collected and analyzed for biological classification. Toxicological results revealed the heavy pollution load of the two sites, nearest to the point pollution source, as the PEC/PNEC ratio exceeded 1.0, while unexpectedly, no risk was detected for the most downstream site, due to the consequent interference of the riparian flora. These toxicological results were in agreement with the ecological analysis: the ecological quality of the two heavily impacted sites ranged from moderate to bad, whereas it was found good for the most downstream site. The results of the study indicate major ecological risk for almost 15 km downstream of the point pollution source and the potentiality of the water quality remediation by the riparian vegetation, proving the significance of its maintenance.

Determination of pesticides and toxic potency of rainwater samples in western Greece.

Rainwater samples from four municipalities located in Achaia Prefecture, Greece, were collected from March to September 2006. The toxic potency of pollutants present in 36 rainwater samples was tested using Daphnia pulex. The pesticide determination was conducted with GC-MS. Only phosphamidon was detected, which appeared in 52% and 13% of the rural and urban areas, respectively. The toxicity of rainwater was determined in 52% and 46.7% of the rural and urban area samples, respectively. Chemical analyses showed that in rural areas, the PO(4)(3-) ions had higher concentrations than in urban areas. On the other hand, the SO(4)(2-), NO(-)(3), and NO(-)(2) anions are more highly concentrated in urban areas. Correlation analysis proved that the toxicity of the rainwater samples is moderate, affected by the presence of the insecticide only in the rural areas. The results indicated that toxicity can be directly assessed via bioassays, even when unknown pollutants are present.