Thallium and lead variations in a contaminated peatland: A combined isotopic study from a mining/smelting area.

Vertical profiles of Tl, Pb and Zn concentrations and Tl and Pb isotopic ratios in a contaminated peatland/fen (Wolbrom, Poland) were studied to address questions regarding (i) potential long-term immobility of Tl in a peat profile, and (ii) a possible link in Tl isotopic signatures between a Tl source and a peat sample. Both prerequisites are required for using peatlands as archives of atmospheric Tl deposition and Tl isotopic ratios as a source proxy. We demonstrate that Tl is an immobile element in peat with a conservative pattern synonymous to that of Pb, and in contrast to Zn.

[Formation of the urinary stones in alkaptonuria patients].

Alkaptonuria is an autosomal recessive disease with late complications (arthritis and ochronosis). Excretion of alkapton (homogentisic acid) in the urine is due to congenital lack of the enzyme homogentisate 1,2-dioxygenase, which mediates the essential step in the catabolism of phenylalanine and tyrosine. Urine excretion of homogentisic acid is very high, urine turns dark if allowed to stand or is alkalinized (a result of formation of polymerization products of alkapton).

Lead fluxes, isotopic and concentration profiles in a peat deposit near a lead smelter (Príbram, Czech Republic).

The content and the isotopic composition of lead (Pb) were studied in a peat deposit on the ridge of the Brdy Hills, in the vicinity of the Príbram metallurgical works, in the Czech Republic. Quadrupole ICP MS was employed to determine the elemental composition and (206)Pb/(207)Pb and (208)Pb/(206)Pb isotope ratios. The individual layers were dated using alpha spectrometric measurement of the (210)Pb activity.

Prevalence of astigmatism among students in northern Greece.

Purpose: To assess the prevalence of astigmatism in a sample of 1738 students (15-18 years old) from Northern Greece.

Methods: Collection of the sample was based on a questionnaire method. Statistical analysis included estimation of the prevalence of astigmatism and the distribution of students according to their cylindrical values.

Prevalence of myopia in a sample of Greek students.

Purpose: An epidemiological study, concerning the prevalence of myopia among the student population (15-18 years old) of Northern Greece, was carried out.

Methods: Specific questionnaires were used in order to collect data on the refractive condition of students.

Results: Myopia prevalence was 36.