DETERMINATION OF Pb AND Mn IN TREE-RINGS

1. Institute of Physics, Laboratory for Plasma Chemistry DETERMINATION OF Pb AND Mn IN TREE-RINGS AND BARK OF LINDEN (Tilia platyphyllos Scop.) BY U-SHAPED DC-ARC D. M. Marković1, I. Novović1, D. Vilotić2, Lj. Ignjatović3 and V. Srećković1 1Institute of Physics, P.O.Box 57, Pregrevica 118, Belgrade, Serbia 2Faculty of Forestry, University of Belgrade, Kneza Viseslava 1, Belgrade, Serbia 3 Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, Belgrade, Serbia • Abstract • As an indicator of environmental pollution we collected tree-rings and bark of Tilia platyphyllos Scop. from urban area of Zemun. An argon-stabilized U-shaped DC arc with a system for aerosol introduction was used for determination of Pb and Mn. The mean concentrations of Pb and Mn in tree-rings and bark are higher than corresponding concentration of Mn • Introduction • Heavy metals are natural components in the environment, but are of concern lately because they are being added to soil, water, and air in increasing amounts. Heavy metals that get into plants, animals, are not degraded, pointing to their accumulation. Increasing urbanization results in the production of a wide range of different pollutants that can have an adverse effect on the surrounding environment. The primary sources of anthropogenic emission of most trace metals are the combustion of fossil fuels and automobile exhaust emission in certain areas and they now exceed or equal their natural emission [1]. Dendroanalysis, the method of analyzing tree-rings for trace metal pollution is based on the assumption that element concentrations in the tree represent element availability in the environment in which the tree was grown [2]. Some authors have successfully shown a correlation between environmental pollution and the concentration of heavy metals in the growth rings [2, 3, 4, 5]. Tree-bark, has been found to be useful bioindicator for monitoring airborne pollution [6, 7]. The knowledge of the elemental content of wood, bark and other plant related materials could be of great interest for industrial and environmental authorities, since monitoring with plants supplies low-cost information on the environmental quality and quantity [8]. Considering the increasingly stricter demands for environmental control, the development of very sensitive methods for the detection of trace elements in natural samples and complex matrices is of great significance. The spectrochemical method applied in the study is a simple method for determination of low concentrations. Apparatus. The experimental operational conditions of our spectrochemical method are presented in Table I. • Solutions. A series of Pb and Mn reference solutions in the range from 10 to 1000 ng/mL was prepared by appropriate dilution of the stock solution (1 mg/mL, Merck). Each solution contained 0.5% potassium chlorate as a spectroscopic buffer. • Sampling location. Tree-ring and bark samples were collected in March 2007 from location Zemun. Each Tilia platyphyllos Scop. core was divided into 3 year segments between 1971 and 2006. • Sampling preparation. Tree-ring samples (3 year segments) were placed in pre-washed (15% H2SO4) 50mL borosilicate glass tubes dried at 70oC for 48h and weighed. Samples were suspended in 10 mL of 70% HNO3 at 80oC for 24h. The cold solution was filtered through acid washed (10% HNO3) Whatman No.42 filter paper and diluted to 50 mL with bidistilled water [9]. • Table I. Experimental operating conditions of our spectrochemical method • Results and discussion • -The mean concentration of Pb and Mn found in Tilia platyphyllos Scop. tree-rings from the location Zemun between 1971 and 2006, in bark and soils are shown in Table II. • Table II. The mean concentrations of Pb and Mn in Tilia platyphyllos Scop. tree-rings from the location Zemun between 1971 and 2006, in bark and soils. • In Table III are shown relations and differences in the mean Pb and Mn concentrations in tree-ring in Tilia platyphyllos Scop., bark and soils from the location Zemun. • Table III. Ratios and differences in the mean Pb and Mn concentrations in tree-rings in Tilia platyphyllos Scop. between 1971 and 2006, bark and soils from the location Zemun. The results presented here, indicate that the values for Pb are higher than values for Mn in all cases except in cases soils (total and available). Concentrations of Pb in soils are lower than concentrations of Mn. However, mean concentrations of Pb in tree-rings and in bark are higher than corresponding concentrations of Mn. Conclusions -In this study Pb and Mn contents in Tilia platyphyllos Scop. tree-rings and soils from the location Zemun were monitored and compared. The mean concentrations of Pb in Tilia platyphyllos Scop. tree-rings and bark are higher than concentrations of Mn in tree-rings and bark. This is mainly consequence automobiles traffic and combustions of fossil fuels. References 1. O. Odukoya, T.A. Arowolo, O. Bamgbose, Environ. Int., 2000, 26, 11-16. 2. K.L. Padilla, K.A. Anderson, Chemosphere, 2002, 49, 575-585. 3. A. Jonsson, M.Eklund, K. Håkansson, J. Environ., 1997, 26, 1638-1643. 4. B.E. Cutter, R.P. Guyette, J. Environ. Qual., 1993, 22, 611-619. 5. G.Liu, Y. Zhang, Y. Qi, L. Zheng, Y. Chen, Z. Peng , Environ. Monit. Assess., 2007, 133, 99-103. 6. H. Schulz, P. Popp, G. Huhn, H.J. Stark, G. Schurmann, Science Total Environ., 1999, 232, 49-58. 7. L. Harju, K.E. 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