This paper outlines research on the use of lignite washery sludge as the amendment for reclamation of lignite mine soil and stimulating poplar trees growth. Sludge is characterized by high total C content ($34%) and high C/N ratio (68:1). The sludge was introduced by ploughing in, down to 20-25 cm depth, in the quantities: 0, 28, 56 and 112 t ha À1 . We have established that the N percentage in poplar leaves decreases with introducing increasing quantities of sludge into the mine soil. On the other hand, the content of B and Cd increased with increasing sludge quantities. The As content in poplar leaves did not correlate with the applied quantities of sludge, but it did with the P, Fe and Zn content in the leaves. Introducing this sludge can have a positive effect on annual tree trunk increment, but only in the subsequent phases of growth. In the first few years an increase of total C content by introducing lignite washery sludge is not sufficient to provide the conditions for faster growth of trees.
Abstract. Soil samples from Novi Pazar (Serbia) and Rožaje (Montenegro) were analyzed by the ORTEC HPGe detectors with relative efficiencies of 35 and 40 % for radioactivity of 226 Ra, 232 Th/ 228 Ac, 40 K and 137 Cs. An average radioisotope activity concentration for Novi Pazar soil was found to be 27.6, 49.5, 585 and 14.9 Bq/kg, respectively; while in Rožaje, 137 Cs activity concentration was found to be significantly higher -from 33.9 to 322 Bq/kg. The obtained results were used to estimate hazard indices, such as radium equivalent activity (none of the localities showed a radium equivalent activity higher than 370 Bq/kg) and annual gonadal dose equivalent to natural radioisotopes, as well as external terrestrial gamma absorbed dose rate of 226 Ra, 232 Th/ 228 Ac, 40 K and 137 Cs, and corresponding annual effective dose -used to evaluate excess lifetime cancer risk (then compared with the world average of 0.2⋅10 -3 , taking into account external terrestrial radiation -outdoor, i.e., average annual effective dose of 0.07 mSv). Vegetation samples from Rožaje -blackberry (Rubus fruticosus), spruce (Picea abies) and beech (Fagus sylvatica) showed 226 Ra activity -4.03, 1.1 and 0.99 Bq/kg, respectively; 232 Th/ 228 Ac -4.5, <1.22 and 2.89 Bq/kg, respectively; 40 K -152, 98.4 and 79.3 Bq/kg, respectively; 137 Cs -3.05, 3.54 and 5.24 Bq/kg, respectively; whilst in Pinus sylvestris from Novi Pazar, they were -2.7, 2.11, 163, <0.34 Bq/kg, respectively. Soil-plant radioisotope transfer factors were also estimated, and compared with typical ranges given in the UNSCEAR 2008 report. Since the most important radiation source for all terrestrial biota is the activity from soil, the dose rates are also evaluated using known internal (and external -in soil) radioisotope activity concentrations, as well as corresponding the dose conversion coefficients for external and internal exposure to particular radioisotope.
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