Bioassays for evaluating the water-extractable genotoxic and toxic potential of soils polluted by metal smelters.

Physicochemical analyses of polluted soils are limited in their ability to determine all hazardous compounds, their bioavailability, and their combined effects on living organisms. Bioassays, on the other hand, can evaluate environmental quality more accurately. This study assesses the genotoxic potential of water extracts from soil polluted with metals (Pb, Cd, and Zn) by the former lead smelter in zerjav, Slovenia using comet assay with Tetrahymena thermophila and human hepatoma cells (HepG2). In addition, the toxicity of soil samples and their extracts was evaluated using Vibrio fischeri and delayed fluorescence of Lemna minor. Chemical analyses of metals using atomic absorption spectrophotometry (AAS) was performed for comparison. Measurements of the total metal concentrations showed that four of five plots near the former lead smelter were highly contaminated with Pb, Cd, and Zn, but the amount of metals in water/soil extracts was low at all the sampling plots. Genotoxicity was demonstrated using T. thermophila for the majority of the extracts, and HepG2 cells for only some of the extracts. Whereas V. fischeri indicated a gradual decrease in soil toxicity with greater distance from the smelter, the toxicity of extracts did not correlate with proximity. Low concentrations of metals in water extracts stimulated L. minor growth. The results indicate that comet assay with T. thermophila and HepG2 cells and the BSPT with V. fischeri are suitable protocols for screening the genotoxic and toxic potential of water/soil extracts by comet assay, whereas chemical analyses of total metal concentrations in soil do not solely suffice for evaluating metal pollution in the environment. Biological assays are thus crucial for risk assessment.

Growth, delayed fluorescence and pigment composition of four Prorocentrum minimum strains growing at two salinities.

Prorocentrum minimum is a potentially harmful and widely distributed marine dinoflagellate. Several P. minimum strains have already been studied, showing phylogenetical relations of strains isolated from the same geographical regions. Similarity among the strains was further examined on the basis of their physiology. Pigment composition and concentration, as well as delayed fluorescence (DF) decay kinetics and intensity, were measured in four P. minimum strains isolated from the Baltic and Adriatic Seas. The strains were grown at two salinities characteristic of the Baltic (8 PSU) and North Adriatic Seas (32 PSU). Strain differences in DF decay kinetics and growth did not always follow their genetic relations. While two strains showed similarities to the previously described strains from the Baltic and Adriatic Seas in DF parameters, the other two strains seemed to be specific. The differences among strains isolated from the same sea could stem from adaptations to conditions in the specific habitats. Cluster analysis based on the ratio of individual carotenoid pigments concentrations to the chlorophyll a concentration or to total carotenoids were not conclusive in showing relations among the strains. Among the measured pigments, only peridinin concentration depended on salinity in all strains.

Delayed fluorescence as a measure of nutrient limitation in Dunaliella tertiolecta.

The applicability of the delayed fluorescence (DF) for the purpose of distinguishing the cells growing in different nutrient conditions was researched on the marine unicellular algae Dunaliella tertiolecta Butcher (Chlorophyta). The DF intensity (DFI), as a measure of living algal biomass, was compared with other biomass measures--the cell concentration, chlorophyll a and fluorescence. The photosynthetic activity index (PhAI), a non-dimensional physiological index of photosynthesis calculated from a combination of DFI and F(0) was introduced. The nitrogen deprivation was indicated by more than 50% drop of PhAI. DF decay kinetics was measured with two different illuminations (<600 nm and >650 nm). The measured curves were divided and the resulting peak utilized for the differentiation among nutrient conditions. DF decay kinetics of D. tertiolecta differed among the cells growing in various nutrient conditions, indicating changes in the photosynthesis physiology.

Growth, delayed fluorescence and pigment composition of four Prorocentrum minimum strains growing at two salinities

Prorocentrum minimum is a potentially harmful and widely distributed marine dinoflagellate. Several P. minimum strains have already been studied, showing phylogenetical relations of strains isolated from the same geographical regions. Similarity among the strains was further examined on the basis of their physiology. Pigment composition and concentration, as well as delayed fluorescence (DF) decay kinetics and intensity, were measured in four P. minimum strains isolated from the Baltic and Adriatic Seas. The strains were grown at two salinities characteristic of the Baltic (8 PSU) and North Adriatic Seas (32 PSU). Strain differences in DF decay kinetics and growth did not always follow their genetic relations. While two strains showed similarities to the previously described strains from the Baltic and Adriatic Seas in DF parameters, the other two strains seemed to be specific. The differences among strains isolated from the same sea could stem from adaptations to conditions in the specific habitats. Cluster analysis based on the ratio of individual carotenoid pigments concentrations to the chlorophyll a concentration or to total carotenoids were not conclusive in showing relations among the strains. Among the measured pigments, only peridinin concentration depended on salinity in all st.

Reflection of hydrocarbon pollution on hepatic EROD activity in the black goby (Gobius niger).

Hepatic ethoxyresorufin-O-deethylase (EROD) activity was measured in black gobies (Gobius niger) collected from seven sampling sites along the Slovenian coast during spawning and non-spawning periods. Sediments from the same sites were tested for their toxicity and for total polycyclic aromatic hydrocarbon (PAH) content. EROD activity was significantly higher during the non-spawning period in winter than during the spawning period in spring and generally correlated well with increased total PAH content in sediments and with sediment toxicity. An 11-fold increase of EROD activity was induced 48h after injecting 10µgg(-1) weight of benzo(a)pyrene into black gobies. On the basis of these results and of its ecological characteristics, the black goby is proposed as a suitable candidate for future biomonitoring programmes.