Abstract: The Canakkale strait (Dardanelles), located between Marmara Sea and Aegean Sea. The concentrations of heavy metals in the twenty - two surface sediment samples from the Dardanelles and Creeks were determined. Total metal concentration in the bulk sediment varies in the range of Al 3.2-5.2 %, Cu 6-50 ppm, Fe 1-3.4 %, Mn 153-1960 ppm, Ni 6-75 ppm , Pb 7-328 ppm , Zn 21-2211 ppm. Al, Cu, Fe and Ni values are low compared to those from the shale averages values of these metals. The relatively high Mn, Pb and Zn values are derived from the rock formations and mineralized zones by the Umurbey, Musako ; y and Saricay Creeks. Pb and Zn pollution in the Saricay Creek sediment is also originated from Industrial and domestic waste discharges of the Canakkale City which its population is 54000.
INTRODUCTION
The strait of Çanakkale (Dardanelles) is a 62 km long water passage connecting the Aegean Sea and Marmara Sea (Fig. 1). Its width varies from 1.3 to 7 km with sill depth of -65 m. It has two-layer flow system, with the upper layer Black Sea waters and the lower layer Mediterranean waters flowing in opposite direction. The surface and subsurface current have velocities 50, 300 and 20, 50 cm sec1, respectively (Defant, 1961; Özsoy et al., 1986). The main source of fresh water and sediments to the Dardanelles is the Karamenderes sream in the Anatolian part. This stream have average suspended sediment discharges of 0.89 106 t year1 (EIE, 1993). There are a lot of minor creek flowing into the Strait of Çanakkale from Thrace (namely Münipbey, Sütlüce, Cumali, Ilgar, Kayaalti, Bigali and Eceabat) and Anatolian side (Lapseki, Umurbey, Yapildak, Musaköy, Kepez and Sariçay).
These creeks are and sediment samples point short in length with small drainage areas (Fig. 1). There are a few scale industries in the area surrounding the Dardanelles and small settlements such as Gelibolu, Lapseki and Eceabat. Their population is 18000, 6000 and 4000, respectively.
The study area is affected by two tectonically active regimes; the active tensional regime in Aegean Sea (McKenzie, 1978; Le Pichon and Angelier, 1981; Seyitoglu and Scott, 1991; Armijo et al., 1996) and Miocene-Pliocene strike-slip faulting, escape tectonics and regional uplift activities along the western part of the Anatolian Fault Zone (Görür et al., 1997; Yaltirak et al., 2000).
| Fig. 1: | (a-b) Map of the dardanelles region showing, its drainage area and sample locations |
| Fig. 2: | Simplified geological map of Marmara surroundings (MTA, 1989; Ergin et al., 1999) |
A geological map of the study area is shown in (Fig. 2). This Fig. 2 indicated that the northern and southern part of the Çanakkale Strait display different geological features. The Anatolian region is mainly built up of various Magmatic (Alkaline and calc-alkaline volcanic rocks) and metamorphic rocks. In Thrace region is mainly dominated with Tertiary-aged sedimentary formations.
The purpose of this study is to investigate the distribution and possible sources of metals in the surface sediment of the Dardanelles. For these study 22 surface sediment sample were collected and analyzed their Al, Cu, Fe; Mn, Ni, Pb and Zn contents.
MATERIALS AND METHODS
Twenty-two sediments samples were collected in the Dardanelles and several small creeks mouth during the 1996 cruises of R/V Arar (Fig. 1). The top of the 1 cm of the sediment was taken and kept in a refrigerator (~2C) before drying and grinding.
In the laboratory, Sediment samples were dried at 105C and ground in a mortar.
| Table 1: | Accuracy of ASS analyses used in this study |
Al, Cr, Cu, Fe, Mn, Ni, Pb and Zn contents were determined by Atomic Absorption spectrophotometer (AAS) after a total digestion. Involving HNO3 + HCIO4 +HF acid mixture. The accuracy of the heavy metal analyses was checked with international standard samples (Table 1). The analytical precision was better than 10 at 95% significance level.
RESULTS AND DISCUSSION
Distribution of heavy metal in the surface sediments: The general geochemical behavior of heavy metal which is known to accumulate in fine-grained sediments (Förstner and Wittmann, 1979; Farrah et al., 1980; Solomons and Forstner, 1984; Emelyanov and Shimkus, 1986; Horrowitz, 1991). There is generally a marked inverse correlation between grain size and metal concentration in the sediment. Çanakkale Strait is a narrow channel where current velocities are very high (Defant, 1961; Özsoy et al., 1986; Oguz and Sur, 1989; Alpar, 2000). As a result large abundance of sand and gravel fraction of sediment of terrigenous origin have been accumulated and the prevailing current patterns for fine-grained materials seem to be erosional rather than depositional (Bayhan et al., 2001). The bottom of the Çanakkale strait is covered largely by terrigenous sand and gravel (Bayhan et al., 2001). In this case, the metal values in the Çanakkale Strait sediments may be low values. In this study all the metal values in strait sediments are lower when comparing sedimentary rocks of these metal values (Table 2, 3). The distribution of Al (3.2-5.2%), Cu (6-50 ppm), Fe (1-3.4%) and Ni (6-50 ppm) contents in the Dardannelles creeks samples mostly resembles that of the shale averages values of these metals (Table 2, 3). Therefore, the geological weathering on land appears to be principal source of these metals in the samples.
Manganese contents amount to between 110 to 1960 ppm with a mean value of 545 ppm Mn (Table 2). Comparison with average shale value of 850 ppm (Krauskopf, 1985) reflects the presence of Mn in the studies samples largely at natural levels. The high (>850 ppm) Mn values are found at two stations, which is located at Musakoy (1945 ppm) and Umurbey (1960 ppm) creeks. This can be readily explained as the result of influx of material from mining activity. The other Mn values in the sediments mostly resemble that of average sedimentary rocks. The Pb contents of the Dardanelles and creeks sediments are lower than the average shale concentrations of 20 ppm Pb (Krauskopf, 1985), except for Umurbey Pb values (324 ppm). The total Zn concentrations range between 21 and 2211 ppm. The highest Zn values (>the shale average value of 90 ppm), 172 and 2211 ppm occurring at station Sariçay and Umurbey creeks sediments. The inter element relationships among the studied heavy metals are given in Table 4.
The data show that; Zn content has positive covariance with Pb (r = 0.99), Mn (r = 0.65) and Cu (r = 0.54) contents of the sediments. Pb values display good correlation with Mn (r = 0.63) values. This is interpreted to be the result of common similar sources. The former is related to the presence of particular geological sources. The main natural sources for these elements are the Pb-Zn and Mn mining activity in the drainage area of creeks (Umurbey, sariçay and Musaköy). The highest Mn, Zn and Pb concentrations are found in the Umurbey creek sediment, southern part of the Çanakkale Strait (Table 2). This indicates that the major supply of those elements to the Çanakkale Strait is the inputs by the Umurbey creeck. Mean Pb-Zn and Mn concentration in the Umurbey creek are higher than those of the other rivers and world average shown in Table 3 although these rivers drain watersheds that are much more industrialized than the Umurbey creeck drainage area. Only Lot (Temple) River sediment shows higher Zn concentrations than Umurbey Creek sediment.
| Table 2: | Heavy metal concentrations of bulk surface sediments in the Çanakkale Marine Strait, River and Creeks |
| Table 3: | Comparison study of heavy metal concentration in sediments of the Çanakkale
strait and creecks with other river systems in the world |
| NA: Not Analyzed | |
| Table 4: | Correlation coefficient of matrix geochemical parameters for 22 sediment samples |
| Fig. 3: | Simplified mines map of the study area (http://www.mta.gov.tr) |
Results from the heavy metal analyses obtained in this study indicated that the concentrations of Al, Cu, Fe and Ni are lower than the shale averages of these metals. A great part of the heavy metal (Mn, Pb and Zn) pollution must be derived from land based natural input and also all the results of heavy metals effected of coastline hinterland. With lesser anthropogenic contribution and carried into the Dardanelles by the Umurbey, Musaköy and Sariçay Creeks. The main source of high heavy metals (Mn, Pb and Zn) is the erosion products of mineralised zones (Fig. 3) in the drainage basins of creeks. The source for anthropogenic inputs into the Dardanelles is mainly derived from Sariçay Creek containing wastes of domestic and industrial activities of Çanakkale City.