All

The concentrations (for two hydrological years) of the heavy metals As, Cd, Cr, Ni and Pb as well as the isotopic 206Pb/207Pb composition in soil layers were studied in a remote mountainous Bulgarian fir (Abies borisii regis) forest in central Greece. The concentrations of metals in the hydrological cycle (bulk deposition and throughfall) were lower than the respective ones in the past in Europe, especially for Pb. In the litterfall consisting of mosses, lichens, insect frass and pollen the concentrations of all heavy metals were found far higher than those in the needle litterfall. An evidence of dry deposition was that all metals had higher concentrations in older needles than the young ones with the exception of Ni. Ni also had the highest concentration in the trunk wood, whereas all the other metals had a very low one. It is highly probable that Ni has an internal cycle within the fir trees. In all compartments of the standing trees the order of concentrations was Ni>Pb>Cr>Cd>As. The concentrations of metals in the ground vegetation were low with the exception of Cd, Cr and Ni in ferns. The concentrations of metals in the FH horizon and mineral soil followed the order Cr>Ni>Pb>As>Cd, whereas in the L layer Ni had the highest value. Despite the remoteness of the fir forest, the percentages of anthropogenic Pb in the soil reached an appreciable 41% in the FH horizon and lowered to 2% in the 20-40 cm layers.

The paper presents a laboratory study of concrete mixes based on the alkali-activation of an industrial by-product, ground granulated blast furnace slag (GGBS). A number of factors potentially affecting the resulting concrete quality in terms of workability and strengths were investigated (namely activator type, molarity, curing conditions and times). The statistical significance of the effect of these factors was supported by ANOVA. Higher workability and strengths (with lower activator concentrations) were obtained for KOH containing mixes. Curing at constant moisture and ambient temperature was successful for most alkaline activators and mixes, which showed good concrete strengths at all curing times; when Na2SiO3 was used in addition to NaOH or KOH activators of moderate to high molarity, strengths exceeded those of Ordinary Portland Cement (CEM-I) concrete of a similar water/cement ratio.

The content of heavy metals in sediment and the aquatic plant Phragmites australis (roots and leaves), collected from six different stations along the Nil river, were determined providing information about heavy metals pollution status of this aquatic ecosystem.
The results showed that the abundance of heavy metals measured in the sediments decreased in the order: Fe>Zn>Pb>Cr>Cd. Apart from Cr and Fe, the concentration of heavy metals exceeded the background values. Metals concentrations were found decreasing with the increasing distance from the river mouth, suggesting that anthropogenic inputs, related to agricultural and domestic discharge into the river, are the major sources of heavy metals in the river sediments and aquatic plants.
The assessment of heavy metals pollution was carried out using geoaccumulation index (Igeo) and enrichment factor (EF). According to the mean values of Igeo, the sediment of Nil river is considered as moderately polluted with Pb and Cd, unpolluted to moderately polluted with Zn and unpolluted with Cr and Fe. The mean values of enrichment factor indicate that all stations presented moderate enrichment with Zn, minor enrichment with Cr and moderately to severe enrichment with pb and Cd in three stations.
Regarding the plant samples, the results showed that the concentration of the elements analyzed in Phragmites australis did not exceed the threshold of phytotoxicity.
Mean concentrations of all elements were less in the plants organs compared to the concentrations of the same elements in the corresponding sediment sample. Metals accumulated by P. australis were mostly distributed in root tissues, as shown by the values of translocation factors (TF) which were <1. A positive association between the metal concentrations in P. australis organs and its environment was also found; this suggests that this plant can be used as biological indicator in biomonitoring studies.