George Siavalas

Responses of Lumbriculus variegatus to Activated Carbon Amendments in Uncontaminated Sediments

Activated carbon (AC) amendment is a recently developed sediment remediation method. The strong hydrophobic organic contaminant sorption efficiency of AC has been shown in several studies, but effects on benthic organisms require more investigation. The AC induced effects on egestion rate, growth and reproduction of Lumbriculus variegatus were studied by applying bituminous coal based AC in three different particle size fractions, namely <63 μm (90%, AC(p)), 63-200 μm (AC(m)) and 1000 μm (AC(g)), to natural uncontaminated (HS) and artificial sediment (AS). Egestion rate, growth and reproduction decreased with increasing AC concentration and finer AC particle fractions, effects being stronger on HS than on AS sediment. Lipid content in AS was reduced already at the lowest AC doses applied (AC(p) and AC(m) 0.05%, AC(g) 0.25%). In addition, hormesis-like response was observed in growth (AS) and reproduction (AS, HS) indicating that AC may disturb organisms even at very low doses. Potential ecological effects need to be further evaluated in an amendment- and site-specific manner.

Concentrations of persistent organic pollutants and organic matter characteristics as river sediment quality indices

ABSTRACT Selected persistent organic pollutants – polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides – were determined in sediments, soils, and crops from the Asopos River area, Greece. The river has been receiving industrial effluents for the last 40 years and has been recently found to be polluted with metals. Sediments were collected in the dry (May) and wet (February) season. Agricultural soils and cultivated crops were sampled from adjacent fields. Polychlorinated biphenyls were below the limit of detection in all samples. In one tomato and two soil samples, DDT and DDE were found. Polycyclic aromatic hydrocarbons were observed in 5% of the sediments and in concentrations ranging from 4 to 57 μg kg−1 dry weight, quite below sediment quality guidelines. Diagnostic ratios of polycyclic aromatic hydrocarbons indicated a strong influence of petrogenic point discharges. In the sediments, silicate minerals dominate over carbonates and the organic carbon content ranges from 0.4% to 3.5%, more than 70% being of natural origin. Compared to other rivers worldwide, the Asopos River was found to be not contaminated with persistent organic pollutants. Point loadings of organic pollutants were evident but continuous discharge is not occurring throughout the river basin.

Phenanthrene Sorption οnto Heterogeneous Sediments Containing Carbonaceous Materials in Fresh Water and in Marine Environments: Implications for Organic Pollutant Behavior During Water Mixing

Phenanthrene is used as a model hydrophobic organic compound to study the sorption properties of the Gulf of Aliveri (Greece) marine sediments. Sorption of hydrophobic organic compounds is mainly related to the organic matter present in the sediments. The presence of particles due to anthropogenic activity in the sediments can highly influence their sorption behavior. Sediments from the Gulf of Aliveri contain different proportions of such particles i.e., lignite, coal, and char. The hypothesis of the present study is that salinity can affect the fate of this pollutant by affecting the degree of sorption nonlinearity and sorption capacity. Since the sorption nonlinearity is a function of heterogeneity, different materials are used to compare their sorption behavior in solutions with and without salinity. Results expected from this study include a) the surface properties of the different sediments and the materials tested and b) sorption capacities in i) fresh and ii) salt water for phenanthrene. In general, it is observed that for carbonaceous particles and sediments containing such particles at lower phenanthrene concentrations, sorption in saltwater solutions is lower than in fresh water solutions.