DETERMINATION OF TRACE ELEMENTS IN THE PLANTS OF MT. BOZDAG, IZMIR, TURKEY

The aim of this study was to determine the current level of atmospheric heavy metal content on the Bozdag Mountain of the Aegean Region, Turkey. Twenty nine different plants were selected to study their potential as biomonitors of trace elements such as Ni, Zn, Fe, Pb, Mn and Cd (μg g-1, dry weight). The samples were collected from two different altitudes of Mt. Bozdag. The concentrations of trace elements were determined by atomic absorption spectrometry. The mean concentrations determined at 1000 m altitude ranged from 0.025 to 1.609, 0.232 to 0.731, 0.578 to 5.983, 0.287 to 0.565 and 0.176 to 2.659 (μg g-1, dry weight), for Ni, Zn, Fe, Pb and Mn, respectively. At the altitude of 1600 m, the values ranged from 0.023 to 0.939, 0.258 to 1.254, 0.839 to 5.176, 0.301 to 1.341 and 0405 to 3.351 (μg g-1, dry weight) for Ni, Zn, Fe, Pb and Mn, respectively. No Cd was detected at either altitude. Statistical significance was determined by the independent sample t-test and comparisons were made in order to determine if there were any differences between the averages of herbaceous and woody plants.


INTRODUCTION
Human activities have globally affected the biogeochemical cycling of heavy metals, resulting in a progressive increase in the flux of bioavailable chemical forms to the atmosphere (Ng et al., 2005;Yorek et al., 2008).There is evidence that increasing exposure to toxic elements in marine and terrestrial organisms is having adverse toxicological consequences (Rana et al., 2004;Katranitsas et al., 2003).In order to evaluate, minimize and avoid the adverse effects of toxic metals, there has been an emphasis on the use of bioindicators to monitor atmospheric quality in both urban and rural environments (Szczepaniak and Biziuk, 2003;Ng et al., 2005).
Biomonitoring is a means to detect the deposition, accumulation and distribution of trace metals in ecosystems.Through the use of different types of vegetation, the levels of atmospheric trace metallic concentrations have been successfully monitored (El-Hasan et al., 2002;Baslar et al., 2003;Dogan et al., 2007;Onder et al., 2007).
Biomonitoring provides the cheapest and simplest method for monitoring trace metal elements in the atmosphere (Kaya and Yaman, 2008;Cayir et al., 2008;Baslar et al., 2009).
Because it is a comparatively simple, cheap and practical method of determining air quality (Cayir et al., 2007), plant biomonitoring is increasingly used as an alternative to the traditional methods, especially in Europe, for studying the regional deposition of natural and anthropogenic pollutants from the atmosphere to the terrestrial environment (Pacheco et al., 2001;Dogan et al., 2007).
The goal of this study was to present and investigate the concentrations of Pb, Cd, Ni, Zn, Fe and Mn on Mt.Bozdag by using plant species.

Sampling area
Ecotourism, which has become increasingly popular in recent years, has been expanding especially in mountains.This particular type of tourism, along with the opportunities provided by the environment, makes the culture and agricultural traditions of the locals available to tourism.Therefore, it has been embraced in many parts of the country and is expanding rapidly.Mt.Bozdag, with its summer pastures as well as archeological and cultural heritage, is among the important ecotourism centers of Western Anatolia.Mt.Bozdag (2159 m) is the highest mountain of the Bozdaglar mountain chain which forms a natural border between the provinces of Izmir and Manisa (Fig. 1).
The samples were collected as suggested by Zechmeister (1995), from 1000 m and 1600 m above the sea level, away from the city with negligible traffic and pollution.

Sample collection and preparation
Samples were collected from altitudes of 1000 and 1600 m in July-August 2006.Twenty nine species were collected in total, of which 15 were from 1000 m and 14 were from 1600 m.The taxonomic determination of the plant species was carried out according to Davis (1965Davis ( -1985)), Davis et al., (1988) and Guner et al., (2001).
For analysis purposes, approximately 100 g of the aboveground parts of bushy species and the fully developed leaves of other plants were collected.The samples were dried in an oven at 80 o C for 24 h, ground in a micro-hammer cutter and fed through a 0.2 mm sieve.The samples were stored in self-sealing plastic bags with silica gel desiccant.Since it was washed after every use, first with absolute alcohol then with distilled water, contamination from the micro-hammer cutter was negligible during the grinding.

Wet digestion procedure
The digestion method is described by Perkin Elmer Corporation (Anonymous, 1996).Samples were immediately analyzed following digestion.The digested plant samples were fed into an airacetylene flame and metal concentrations were determined by flame atomic absorption spectrometry (FAAS).The analyses were carried out in triplicate.

Reagents
Unless otherwise specified, all chemicals used were of analytical reagent grade.Triple distilled water was used throughout the experiments.By diluting the stock standard solution with water, working metal standard solutions were prepared just before use.

Instrumentation
Determination of heavy metals was performed with a Perkin Elmer Analyst 700 model flame atomic absorption spectrometer furnished with deuterium background correction, hollow cathode lamps (HCl) and an acetylene burner.The absorption measurements were performed under the conditions recommended by the manufacturer.Before determination, a Cole-Parmer microfiltration apparatus with a membrane filter (0.45 μm pore size manufactured by Micro Filtration Systems, MFS) was used for aqueous phase filtration.

Data analysis
Concentration values are given as mean±standard error (SE).Statistical significance was determined by the One-sample t-test.In the independent t-test, comparisons were made in order to determine whether there were any differences between the averages of the sites assumed as polluted and the control region.Differences at P<0.05 were considered to be significant.A Statistical Package was used in the analysis of t-test for the data.

RESULTS AND DISCUSSION
Levels of the trace elements Cd, Ni, Zn, Fe, Pb and Mn (μg g -1 , dry weight) in plant samples collected from different altitudes of Mt.Bozdag are given in Tables 1 and 2. The plants used as biomonitors were sampled with 29 different species at two different altitudes in the Mt.Bozdag.Atomic absorption spectrometry was used in order to determine the concentrations of metals.The following mean concentrations were determined at an average altitude of 1000 m: The contents of Ni, Zn, Fe, Pb and Mn (μg g -1 , dry weight) ranged from 0.025 to 1.609, 0.232 to 0.731, 0.578 to 5.983, 0.287 to 0.565 and 0.176 to 2.659, respectively (Table 1).On the other hand, at an average altitude of 1600 m, the contents of Ni, Zn, Fe, Pb and Mn (μg g -1 , dry weight) ranged from 0.023 to 0.939, 0.258 to 1.254, 0.839 to 5.176, 0.301 to 1.341 and 0405 to 3.351, respectively (Table 2).No Cd values were determined in the samples collected from either height.
The aggregation of investigated trace elements in plants collected from 1000 m on Mt.Bozdag is presented in Table 1.From the table it can be seen that the Ni content was the highest in Lapsana communis (1.609 μg g -1 ), and the lowest in Phillyrea latifolia (0.025 μg g -1 ).Zn content was the highest in Cercis siliquastrum (0.731 μg g -1 ), and lowest in Juniperus oxycedrus subsp.oxycedrus (0.232 μg g -1 ).The Fe content was the highest in Stachys cretica subsp.smyrnaea (5.983 μg g -1 ), and lowest in Pinus brutia (0.578 μg g -1 ).The Pb content was the highest in Urtica dioica (0.565 μg g -1 ), and in Pinus brutia (0.287 μg g -1 ) it was the lowest The.Mn content was the highest in Lapsana communis (2.659 μg g -1 ), and lowest in Pinus brutia (0,176 μg g -1 ).At 1000 m, the highest values were recorded for Ni and Mn in Lapsana communis, for Zn in Cercis siliquastrum, for Fe in Stachys cretica subsp.smyrnaea and for Pb in Urtica dioica.
The sources for accumulation of some trace elements have been explained by various researchers.For example, anthropogenic activities are the main sources of Pb and Zn according to Alfani et al., (2000), Blok (2005) and Oliva and Rautio (2005).The burning of coal and oil, production of Cu, Ni and Pb, mining operations, steel works and cement industry are cited as major anthropogenic sources of Ni (Nriagu and Pacyna, 1988).Although airborne Mn mainly comes from soil (Bargagli et al., 2003;Oliva and Rautio, 2005), and Fe originates from both anthropogenic and na- tural sources (Oliva and Rautio, 2005), it was reported that the contamination of soil by Fe and Mn highly affects plants in the Mediterranean climate zone (Loppi et al., 1999).
The results of statistical analysis show that the comparison of heavy metal pollution values of herbaceous and woody plants for Fe and Mn was meaningful (P<0.05),whereas it was not for Ni, Zn and Pb (Table 3).When the mean values of heavy metal pollution in herbaceous and woody plants were compared, the accumulation was higher in herbaceous plants for Fe and Mn, with a statically meaningful difference.
In this study, 29 different plants that are used as biomonitors were sampled at two different altitudes (1000 m and 1600 m) of Mt.Bozdag in order to investigate the levels of the trace elements Cd, Ni, Zn, Fe, Pb and Mn (μg g -1 , dry weight).The obtained trace element values were shown to be below the values of control samples from other studies carried out in clean areas.As a result, low element values are considered to be soil-oriented.We are convinced that this study will contribute to future studies on pollution in the same or similar localities.Alfani, A., Baldantoni, D., Maisto, G., Bartoli, A., and A. Virzo De Santo (2000).Temporal and spatial variation in C, N, S and element contents in the leaves of Quercus ilex with in the urban area of Naples.Environ.Pollut.109, 119-129.

Table 3 .
Statistical analysis values of herbaceous and woody plants.