Synthesis of anti-12-hydroxyendrin and 12-ketoendrin,the two major mammalian metabolites of endrin

The first synthesis of $\text{syn}$ and $\text{anti}$ 12-hydroxylated derivatives of endrin (and thence 12-ketoendrin) has been accomplished in three steps starting from hexachlorocyclopentadiene and 7-benzoyloxy [2.2.1]hepta-2,5-diene.     

Precipitation, pH and metal load in AMD river basins: an application of fuzzy clustering algorithms to the process characterization

In the present work, Acid Mine Drainage (AMD) processes in the Chorrito Stream, which flows into the Cobica River (Iberian Pyrite Belt, Southwest Spain) are characterized by means of clustering techniques based on fuzzy logic. Also, pH behavior in contrast to precipitation is clearly explained, proving that the influence of rainfall inputs on the acidity and, as a result, on the metal load of a riverbed undergoing AMD processes highly depends on the moment when it occurs. In general, the riverbed dynamic behavior is the response to the sum of instant stimuli produced by isolated rainfall, the seasonal memory depending on the moment of the target hydrological year and, finally, the own inertia of the river basin, as a result of an accumulation process caused by age-long mining activity.     

Geochemistry and bioavailability of metals in sediments from northern San Francisco Bay

In this study, metals (Be, Cr, Mn, Fe, Ni, Cu, Zn, Ag, Cd, Pb and Hg) in the fine-grained fraction (<63 microm) from 12 sites at different locations in northern San Francisco Bay over a year period from March 2000 to March 2001 were analyzed after acid extraction. The results showed that metal concentrations in the sediments varied from site to site, whereas some of them were found elevated with respect to the sediment of Tomales Bay, CA, which has little contamination history, indicating an enrichment of the metals in the sediment samples analyzed. Sediment toxicity and bioaccumulation evaluation by a clam species, Macoma nasuta, exposed to the sediment samples collected from the six sampling sites was carried out. The results showed that the sediment samples tested significantly reduced clam survival. Toxicity of the sediments to the clam was, in part, related to elevated metal concentrations in the sediments. In order to examine geochemistry of the metals and to understand potential correlations between metal concentrations and geochemical matrix elements of the sediments, bioavailability and toxicity of the metals, detailed analysis of metal concentrations associated with total organic carbon and the Fe-oxy-hydroxides in the sediment samples was performed. The analysis showed that sediment geochemistry appeared to influence metal bioavailability and may have important impacts on the toxicity of these metals to the clam.     

Review and assessment of models for predicting the migration of radionuclides through rivers

The present paper summarises the results of the review and assessment of state-of-the-art models developed for predicting the migration of radionuclides through rivers. The different approaches of the models to predict the behaviour of radionuclides in lotic ecosystems are presented and compared. The models were classified and evaluated according to their main methodological approaches. The results of an exercise of model application to specific contamination scenarios aimed at assessing and comparing the model performances were described. A critical evaluation and analysis of the uncertainty of the models was carried out. The main factors influencing the inherent uncertainty of the models, such as the incompleteness of the actual knowledge and the intrinsic environmental and biological variability of the processes controlling the behaviour of radionuclides in rivers, are analysed.     

Accumulation and release of 241Am by a macrophyte of the Yenisei River (Elodea canadensis)

The source of radioactive contamination of the Yenisei River floodplain, including contamination with transuranic elements, is the Mining-and-Chemical Combine of the Russian Ministry of Atomic Energy, which has for many years been producing weapons-grade plutonium. Transuranic elements have been detected not only in the soil and sediment of the river but also in the biomass of aquatic plants. This work is an investigation of accumulation and release of 241Am by a submerged macrophyte of the Yenisei River (Elodea canadensis) in laboratory experiments. In 2000-2003, laboratory experiments were carried out with biomass of E. canadensis Mich. and filtered river water. The samples were collected from the Yenisei River upstream of the discharge of the Combine's radioactive effluent. The experiments showed that 241Am is accumulated by Elodea biomass: the activity concentration of 241Am can reach 3280+/-240 Bq/g, with the concentration factor for 241Am 16 600+/-2200l/kg. Results of chemical fractionation have proved that in the course of 241Am accumulation by Elodea biomass, 241Am tightly bound to biomass increases from 11% to 27% of the total 241Am in the biomass. Release of 241Am from the decaying Elodea biomass has been evaluated experimentally. By the end of the experiment (lasting up to 127 days), the Elodea plants had lost up to 65% of their initial 241Am activity and the rate of 241Am release into the water environment reached 23 Bq/day.     

Accumulation of Chernobyl-derived 137Cs in bottom sediments of some Finnish lakes

The amount and vertical distribution of Chernobyl-derived 137Cs in the bottom sediments of some Finnish lakes were studied. Sediment and surface water samples were taken in 2000 and 2003 from 12 stations in nine lakes and the results were compared with those obtained in corresponding surveys carried out in 1969, 1978, 1988 and 1990. Each of the five deposition categories of Chernobyl fallout in Finland were represented. The depth profiles of 137Cs in the sediments showed considerable variety in the lakes studied. The peak values varied between 1.5 and 46 kBq kg(-1) dry wt. The size and shape of the peak did not always correlate with the amount of deposition in the area, but on the other hand, reflected differences in sedimentation processes in different lakes. In some of the lakes the peak still occurred in the uppermost (0-2 cm) sediment layer, but in an extreme case the peak occurred at a depth of 22-23 cm corresponding to a sedimentation rate of 16 mm year(-1) during the 14 years after the Chernobyl accident. The total amounts of 137Cs in sediments varied from 15 to 170 kBq m(-2) at the sampling stations studied. Since 1990, the amounts have continued to increase slightly in two lakes, but started to decrease in the other lakes. In most of the lakes, the total amounts of 137Cs in sediments were about 1.5-2 times higher than in local deposition. In two lakes, the ratio was below 1, but in one case 3.2. Compared with the total amounts of 137Cs at the same stations in the late 1960s and 1970s, the values were now at their highest, at about 60-fold. The most important factors affecting 137Cs values in sediments were the local amount of deposition and the type of the lake and the sediment, but in addition, there were a number of other factors to be considered.     

Gradient Genogeographic Analysis of <Emphasis Type="Italic">Pinus sylvestris</Emphasis> L. Populations in Europe

Gradients of Nei's genetic distances between 15 samples of Pinus sylvestris L. trees were analyzed along three submeridional transects, from Scandinavia to the Mediterranean and Transcaucasia. As a result, distinct chorogenetic differentiation was revealed between the populations of this species growing in climatically specific regions of northern and southern Europe. Considerable Nei's distances (DN = 0.045–0.056) and their gradients, combined with differences in stable phenotypic characters (the composition of monoterpenes and morphological parameters of cones) determined at the Pyrenean and Caucasian mountain borders, suggest that the P. sylvestris species structure includes two South Eurasian subspecies, the Pyrenean P. sylvestris L., ssp. iberica Svoboda and the Transcaucasian P. sylvestris L., ssp. hamata (Stev.) Fomin.