Distribution and chemical speciation of arsenic and heavy metals in highly contaminated waters used for health care purposes (Srebrenica, Bosnia and Herzegovina).

Determination of distribution and chemical speciation of arsenic and heavy metals in five acidic springs and in the receiving river near Srebrenica (Bosnia and Herzegovina) was carried out. These waters were used for centuries, and continue to be used, for health-care purposes. The composition and properties of all springs and the river water (after all inputs) resembled that of an acid mine drainage. Very low pH (<3.3), high sulphate concentration and extremely high contents of most of the measured elements (25) are found in all springs (e.g. arsenic and iron maximal concentration of 6.6 and 500 mg L(-1), respectively). Although of small discharge, spring waters caused the decrease of the receiving river pH (from 7.3 to 3.4) and the considerable increase of the concentrations of elements. The enrichment factor for the studied elements ranged from 1.2 for Sr up to 425 for As. In acidic spring waters, all elements were predominantly present in dissolved form. Elements associated to freshly-formed hydrous ferric oxide were prevailing in particulate forms only at the two most upstream sites in the river with pH>7. Geochemical speciation modelling (PHREEQC and WHAM-VI) revealed that As was mainly present as As(V), and Fe as Fe(III). Complexation of dissolved metals by organic matter was predicted to be significant only for the two river sites with neutral pH.

Voltammetric procedure for trace metal analysis in polluted natural waters using homemade bare gold-disk microelectrodes.

Voltammetric procedures for trace metals analysis in polluted natural waters using homemade bare gold-disk microelectrodes of 25- and 125-microm diameters have been determined. In filtered seawater samples, square wave anodic stripping voltammetry (SWASV) with a frequency of 25 Hz is applied for analysis, whereas in unfiltered contaminated river samples, differential pulse anodic stripping voltammetry (DPASV) gave more reliable results. The peak potentials of the determined trace metals are shifted to more positive values compared to mercury drop or mercury-coated electrodes, with Zn always displaying 2 peaks, and Pb and Cd inversing their positions. For a deposition step of 120 s at -1.1 V, without stirring, the 25-microm gold-disk microelectrode has a linear response for Cd, Cu, Mn, Pb and Zn from 0.2 microg L(-1) (1 microg L(-1) for Mn) to 20 microg L(-1) (30 microg L(-1) for Zn, Pb and 80 microg L(-1) for Mn). Under the same analytical conditions, the 125-microm gold-disk microelectrode shows linear behaviour for Cd, Cu, Pb and Zn from 1 microg L(-1) (5 microg L(-1) for Cd) to 100 microg L(-1) (200 microg L(-1) for Pb). The sensitivity of the 25-microm electrode varied for different analytes from 0.23 (+/-0.5%, Mn) to 4.83 (+/-0.9%, Pb) nA L micromol(-1), and sensitivity of the 125-microm electrode varied from 1.48 (+/-0.7%, Zn) to 58.53 (+/-1.1%, Pb nA L micromol(-1). These microelectrodes have been validated for natural sample analysis by use in an on-site system to monitor Cu, Pb and Zn labile concentrations in the Deûle River (France), polluted by industrial activities. First results obtained on sediment core issued from the same location have shown the ability of this type of microelectrode for in situ measurements of Pb and Mn concentrations in anoxic sediments.

Electrochemical determination of dissolved uranium in Krka River estuary.

The applicability of the previously developed method for electrochemical determination of dissolved uranium concentration has been tested on natural water samples taken from the Krka river estuary during various seasons and along different depth profiles. The method is based on the following treatment of the sample: destroying the uranyl-carbonato complexes by adjusting the pH to 3, enabling the formation of adsorbable uranyl-hydroxo complexes by adjusting the pH to 6.5-7.0 and measurement by cathodic stripping voltammetry technique. As the signal of the dissolved uranium reduction is sometimes masked by the signal of the matrix of the sample, a resolution enhancement including digestion and/or deconvolution has to be applied. The measured concentration of dissolved uranium varies in the range from 0.4 to 3.3 x 10(-8) mol l-1, corresponding to the data found in the literature. The depth profile of dissolved uranium concentration distributions shows conservative behaviour. The X-ray fluorescence spectroscopy (XRF) confirmed the applicability of the method, yet pointing out to its limitations caused by the matrix of the solution.

[Intrauterine growth retardation of newborns with congenital anomalies]. / Intrauterini zastoj rasta novorodencadi s kongentalnim anomalijama.

The authors examined 11,799 newborns whose intrauterine life lasted from 28 to 42 weeks. In the group of dysmature infants (443) malformations were present in 11% and in the group of prematures (841) in 4.3%. Malformations were divided according to localization. The most significant difference was observed in the occurrence of malformations of the extremities (dysmature infants 27.17% and prematures 15.79%). It is concluded that malformations appear to be considerably more frequent in dismature infants than in prematures and that by their presence they affect the child's intrauterine growth.