waste disposal on karstic

Geosciences JournalVol. 15, No. 3, p. 339 − 348, September 2011DOI 10.1007/s12303-011-0021-0 ⓒ The Association of Korean Geoscience Societies and Springer 2011

Waste disposal on karstic terrain: a case study from the ancient marble quarries in Iznik (Nicaea), Turkey

ABSTRACT: This study is conducted in Iznik, a city situated inthe Marmara region of Turkey. There are number of ancient mar-ble pits in the area, some of which are used as sewage and solidwaste dump sites. This study is aimed at investigating the hydro-geological and hydrogeochemical properties of Iznik plain withspecial emphasis on these waste sites. In terms of geological fea-tures, Derekoy metamorphics are basement rocks that consist ofgraphite schist, muscovite-quartz schist and marble lenses. SinceIznik marble was used as a natural construction material in thearea since in the Roman era, 20 ancient marble quarries in dif-ferent sizes existed in and around the study area. Wastewaterfrom the city of Iznik and surrounding residential areas was dis-posed in three of these ancient marble quarries. In terms ofhydrogeological features, the Iznik marble and alluvium unitsconstitute the main aquifer system in the study area. Because ofthe highly fractured structure of the Iznik marble, the wastewa-ter in the quarries was able to move rapidly within the rock.Analyses of groundwater samples revealed that the wastewaterflowing in the marble unit discharges eventually into the alluvialunit and thereby affecting groundwater quality around theantique quarries. Based on chemical analyses results, the waste-water was Na-Cl water type and contained high concentrationsof Na (3260 mg/l), K (903 mg/l) and Cl (10396 mg/l). Samplesfrom wells down gradient of the wastewater source had compar-atively higher Na, K and Cl concentrations.

Key words: ancient quarries, karstic terrain, sewage and waste disposal,Iznik (Turkey)

1. INTRODUCTION

Karstic and alluvial systems are main aquifer materialsaround the world and many communities supply their drink-ing and irrigation water demand from these aquifers. Karstaquifers typically exhibit complex and unique geologicaland hydrogeological characteristics. The permeability ofcarbonate rocks arises primarily from the enlargement ofjoints and bedding plane partings. As the aquifer materialis continuously dissolved by circulating groundwater, frac-

tures and fissures are formed creating primary porosity forthese formations. Therefore, contaminants in karstic aqui-fer systems can be transported rapidly and can influencethe quality of important water resources. In this regard,carbonate rocks such as marble, limestone and dolomitethat form important aquifers are very vulnerable to con-tamination and are easily contaminated if no precautionarymeasures are taken. (Bodhankar and Chatterjee, 1994; Caloand Parise, 2009).

Some karstic features such as dolins and ponors (shallowhole) are used for waste disposal in some countries (Kac-aroglu, 1999). Contaminants from the karstic surfaces easilyfind their way in to karstic aquifers through dolins, ponorsor open karst fractures (Vesper et al., 2000). Transport of thecontaminants is very rapid in such fractured zones whencompared to granular aquifer system. Flow of groundwaterand transport of contaminants in karstic aquifers mainlyoccur in complex conduit systems under relatively high flowvelocity. Therefore, such aquifer systems should be protectedfrom waste disposal activities due to absence of a protec-tive cover and retarding mechanisms. Several studies areconducted to determine the vulnerability of karstic aquifersto pollution. A karstic aquifer vulnerability assessment tech-nique (EPIK) is widely used to determine karst protectionzones (Doerfliger et al., 1998). This vulnerability techniqueincludes several hydrogeological parameters such as epikarst,protective cover, and infiltration ratio and karst networksystem. A main objective of this vulnerability technique isto assess the recharge mechanism of groundwater in karsticaquifer.

In addition to karstic systems, the widely observed allu-vial systems are another important water resource in manyparts of the world and are proved to be an important sourceof groundwater for domestic and irrigational water supply.Alluvial aquifers, which constitute the most important hydro-geological reservoirs, are typically unprotected from surfacecontaminants and are easily contaminated if no precaution-

Celalettin Simsek*

Ali Bahadir YavuzHakan Elci

Alper ElciOrhan Gunduz }

Department of Drilling, Torbali Technical Vocational School of Higher, Dokuz Eylul University, Torbali 35860, Izmir, TurkeyDepartment of Geological Engineering, Dokuz Eylul University, Izmir 35160, TurkeyDepartment of Drilling, Torbali Technical Vocational School of Higher, Dokuz Eylul University, Torbali 35860, Izmir, Turkey

Department of Environmental Engineering, Dokuz Eylul University, Izmir 35160, Turkey

*Corresponding author: [email protected]

340 Celalettin Simsek, Ali Bahadir Yavuz, Hakan Elci, Alper Elci, and Orhan Gunduz

ary measures are taken. Solid and liquid wastes play thegreatest role in the contamination of these aquifer systems(Appleyard, 1996; Simsek et al., 2006). Limestone, dolo-mite and marble are quarried world-wide and used forcement manufacture as an aggregate, for high grade build-ing stone, for abrasives and for many other uses (Watson etal., 1997). When limestone, dolomite and marble quarriesare used as waste disposal sites, groundwater pollutionoccurs. If a landfill was constructed in an area of karst ter-rain especially active karst region or quarries without pro-tected cover design, the groundwater could be polluted by

microbial and other hazardous pollutants (Davis, 1997).A major karstic aquifer is present in the vicinity of the

city of Iznik. Based on the statements and observations oflocal inhabitants, liquid wastes (mostly domestic waste-water) of Iznik have been disposed in ancient marble quar-ries in karstic aquifer for many years. These facts formedthe motivation for this study with the objective to charac-terize the hydrogeology and the hydrogeochemistry ofgroundwater in the vicinity of the karstic aquifer whichreceived significant quantities of sewage and solid wastesand is hydrologically connected to the alluvial aquifer.

Fig. 1. Location map of the study area (Fault zones taken from Franz et al., 2006).

Influences of waste disposal in ancient marble quarries in Iznik (Nicea), Turkey 341

2. DESCRIPTION OF THE STUDY AREA

2.1. Geology of the Area

In terms of tectonics, the study area lies within Alpine-Himalayan orogenic belt. The W-E tectonic line controlsseismic activity in the region. The commonly known NorthAnatolian Fault Zone (NAFZ) lies near the study area (Yil-maz et al., 1997). The NAFZ is a continental transformfault system (strike-slip) and is considered to be the bound-ary of the European plate in the north and the Anatolianblock in the south as shown in Figure 1 (Franz et al., 2006).Being situated in close vicinity to the fault zone, lakesManyas, Ulubat, Iznik and Sapanca are considered to beformed by tectonic activity, where many earthquakes haveoccurred in past and in recent times (Franz et al., 2006).The study area includes Lake Iznik, the largest a freshwaterbody in Marmara Region of Turkey and its immediate vicin-ity (Fig. 1).

The geological map of the study area is shown in Figure2. The complex orogenic belt within the study area com-prises a large variety of rock types including Paleozoicmetamorphic shale interbedded with marble (Bargu, 1978;Bargu, 1982; Genc, 1987). The geological studies con-ducted in the area revealed that the Derekoy metamorphicsconstitute the basement rock of the study area, consistinggraphite schist, muscovite-quartz schist and marble lenses(Bargu, 1978). Iznik marble unit that has dense fracturesand a thin layer with heteroblastic texture overlays the

schist unit. Since Iznik marble was used as natural con-struction material in the Roman era, 20 ancient marblequarries of different sizes were opened in the study area formarble production (Yavuz et al., 2009). The quaternaryaged alluvium overlay these units and is observed in thevicinity of Lake Iznik. According to a previous study, sed-imentary alluvial and fluvial deposits consist of gravels,sands and clays and reach a thickness of around 250 m(Franz et al., 2006).

2.2. Hydrogeology of the Area

Based on the previous studies, Lake Iznik is located inthe Mediterranean climate zone. This specific, moderateclimate is characterized by warm, dry summers (May–October) and mild, wet winters (November–April). Aver-age temperatures range between 24 °C in July and 6 °C inJanuary. Mean annual temperature in this region is about14 °C and mean annual precipitation is about 630 mm.Most precipitation falls during the winter and spring sea-son (Franz et al., 2006).

Lake Iznik is the main surface water reservoir in thearea. General drainage lines are from the east to the westand northeast to southwest. There are two major aquifersystems in the study area. The first aquifer is formed fromPaleozoic aged marble exhibiting semi-confined karsticaquifer characteristics. The second aquifer is formed fromthe alluvial sediments and demonstrates unconfined surfi-cial aquifer properties (Fig. 2). The alluvial aquifer near

Fig. 2. Geological map of the study area (modified from Bargu, 1978).


the study area was described as an important aquifer(Yuzer, 1997). These two aquifer systems are connectedwith hydraulic interaction. The semi-confined Paleozoicaged Marble aquifer is the karstic aquifer of the region,within which groundwater flows from northeast to south-west towards Lake Iznik, and is in hydraulic interactionwith the lake. The source of recharge to this aquifer is theprecipitation infiltrating from the outcropping rechargezones to the east of the basin as well as the leakage fromprecipitation through permeable and fractured zones. Sev-eral important drinking and irrigation water supply wellsare drilled in this main alluvium aquifer that has depthsranging from 6.0 to 60.0 m with flow rates between 1 and5 L/s. The depth of groundwater in the main aquifer rangesbetween 5 and 17 m. Wells in this aquifer provide yields ashigh as 3 L/s during winter months and less than 1 L/s dur-ing summer months. These are typically hand-dug wellswith depths ranging between 4 and 6 m, and water levelsranging between 1 and 3 m. According to isotopic com-position, cold groundwater from the Marmara region ploton meteoric water line (Eisenlohr et al., 1997).

3. METHODOLOGY

Research was conducted to understand the waste sites ongroundwater quality. Firstly, the general geology of thestudy area is assessed through field exploration and eval-uation of previous research. Secondly, the fracture analysesof marble unit is conducted by detailed fracture zoneobservations in three marble quarries near waste sites. Theproperties of the rock mass such as the number of discon-tinuity sets, spacing and the aperture of the discontinuitiesare important parameters affecting the permeability ofrocks (Goodman, 1989). Therefore, detailed discontinuitymeasurements of quarry benches were conducted to deter-mine these mass properties of Iznik ancient marble quar-ries that were used as disposal sites for waste material.Initially, discontinuity orientations were measured on themarble quarry benches by using compass and obtained dateswere analyzed with stereo computer program. Finally, asampling program was implemented to assess the chemicalproperties of the groundwater in the area. The water qual-ity sampling program was performed with a total of twelvesampling locations (Fig. 3). Ten out of these locations wereproduction wells drilled in the alluvial surficial aquifer fordomestic water supply purposes. The sampling locationswere selected such that an optimum uniform spatial dis-tribution was obtained in order to achieve highest possibleaccurate representation of groundwater quality in the surf-icial aquifer. The remaining two water samples were takenfrom Lake Iznik (Iz-12), and from the wastewater thatflowed from the waste disposal site D (Iz-9).

Prior to groundwater sampling, wells were operated fora minimum of 15 minutes until electrical conductivity of

water was stabilized. Then, two samples were collectedfrom each sampling location (i.e., 1000 mL for standardanion and cation analysis and 50 mL for trace element andheavy metal analysis) resulting in 24 sample bottles for alltwelve sampling locations. All samples were filtered (0.45µm) and stored at 4 °C in polyethylene bottles until ana-lyzed for major anions and cations. All 50 mL samples col-lected for trace element and heavy metal analysis wereacidified to pH less than 2. The temperature, pH, and elec-trical conductivity (EC) were measured on-site using a por-table multi-parameter probe. Heavy metals and trace elementanalysis were performed with ICP-MS in ACME Labora-tories (Canada). Anions (Chloride, nitrate and sulfate) andcations were measured using the ion-chromatographymethod in Dokuz Eylul University laboratories. Due to itshigh ionic strength, wastewater nitrate concentration wasanalyzed using spectrophotometric methods. Bicarbonateions were quantified with titrimetric methods. To evaluatethe water chemistry of all groundwater samples, Aquachemv3.70 computer program was used.

4. RESULTS AND DISCUSSION

4.1. Ancient Marble Quarries in Karst Terrain and Waste Disposal

Use of marble as a construction material is common inTurkey since ancient times. The roman theatre of znik,whose main structure was entirely built using solid blocksof grey marble, strongly suggests that a large supply sourceprobably existed in the vicinity of the city. Three largeancient marble quarry districts were easily located on thehills 2 km northeast from the city centre of znik. The firstdistrict, Sarlkaya, includes two large quarries, one stillworking and the other is known locally as Delikta . Theother two extraction districts are located more to the eastand include 2 and 13 different quarries, respectively. Thenumber of the existing districts and the large size of someof the quarries, suggest that the marble, besides being usedfor the need of the city, was very probably exported else-where. The znik marble was used not only for the theatrestructure, but also for the production of architectural ele-ments (column capitals, shafts and bases), sarcophagi andreliefs, as attested by the objects in the local Museum andseveral items on display in Museum of zmit (the ancientand renowned marble trade centre of Nicomedia) (Yavuz etal., 2009).

There are 20 ancient quarry pits on this marble formation(Fig. 2) and three of these quarries received liquid waste asshown in Figure 3 and denoted by Quarry A, B and C. Thefirst one is located near the Iznik Center (Quarry A). Thesecond one (Quarry B) is situated near Quarry A whereasthe third one (Quarry C) is located at the highest topo-graphic level (Fig. 3). All three sites are now used as liquid

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waste disposal locations. The site labeled as D on the mapis a solid waste disposal location with no impermeable bar-riers or any control and monitoring systems. This site isalso situated on the vulnerable marble unit. A considerableamount of leakage from the accumulated solid waste couldbe detected at the toe of the waste hill.

Based on this motivation, some fracture zone analysesare conducted for several open pits especially used as wastedisposal sites. Three tectonic joint sets are concentrated at40/68, 194/84 and 254/82 directions in Quarry A, and twotectonic joint sets are concentrated at 84/66, 273/78 direc-tions Quarry B and at 76/77, 344/72 directions in QuarryC. Quarries A, B and C also show the presence of severalirregular joint planes, clustered at different locations of thestereographic projection with low percentages. The frac-ture spacing measurements made along the scanline run-ning 1 m above the ancient quarry floor and parallel to thebench faces and obtained spacing data of the discontinui-ties were analyzed by using the technique suggested byPriest and Hudson (1976).

The mean fracture spacing of the studied Iznik ancientmarble quarries are found to vary between 37 and 84 cm.The fracture aperture measurements were made along thescan line running 1 m above the ancient quarry floor and

parallel to the bench faces by using caliper equipment.During this work, the fracture infilling material types werealso determined. Analysis of the fracture aperture measure-ments of all Iznik ancient marble quarries were found tovary between 1 and 50 mm. These fractures were mostlyclean and did not contain any filling material. On the otherhand, several irregular calcite and clay mineral filled largeaperture fractures were found that are larger than 50 mm.

According to field studies, the slopes of the fracture werenear vertical and had a general direction NW-SE. This frac-ture direction controls the groundwater movement and theextent of waste entering the marble unit. Precipitation andthe disposed liquid waste vertically infiltrate mainly alongthe fracture in marble units and then follow a flow pathtowards the lake along the impermeable schist-marble con-tact. A conceptual cross-sectional diagram of this movementis shown in Figure 4. During this vertical descend, precip-itation and waste material also demonstrate short circuitingpatterns through movement in vertical joints and siphonsare observed as seen in Quarry A and shown in Figure 4.Consequently, leakage from sewage pond exfiltrates fromthe joint as seen in Figure 4. Thus, waste material infil-trating from an elevation of 141 m exfiltrates at an eleva-tion 121 m within a short horizontal distance of about 30 m

Fig. 3. The locations of waste sites and surface and groundwater samples.


(Fig. 4). This mechanism demonstrates the primary move-ment of waste deposited in these ancient quarries. Accord-ing to hydrogeological conceptual model, the liquid wasteflow in marble unit is transported as conduit flow regime.When reached the alluvium aquifer, this flow regime becomediffuse and disperses in granular aquifer.

4.2. Groundwater Quality

Groundwater levels in the alluvial aquifer are 5−6 mabove sea level. Based on the analysis of the water table,the groundwater flow direction in the alluvial aquifer wasdetermined to be from marble sector to Iznik lake (fromnortheast to southwest). It is considered that the karsticrocks in the eastern parts of the area are quite permeableand feed the alluvial aquifer.

The physical properties and chemical analyses results forall collected samples are provided in Table 1. All samplesexcept for Iz-9 and Iz-12 are collected from groundwaterproduction wells. The Iz-9 sample represents a sample ofwastewater that flowed from the waste site D and Iz-12 isa surface water sample of Lake Iznik. According to the state-ments of the local residents, wastewater was dischargedinto three quarry pits (A, B and C). However, the durationand extent of the discharge is unknown. Because of the

fractured nature of the marble aquifer that facilitates infil-tration, only a small portion of the wastewater remained inthe pits. Some precipitates and residuals were visible onthe walls of the pits (Fig. 4). The remaining wastewater inthe pits had a dark brown color and had an electrical con-ductivity of 27000 µS/cm. The chemical analyses results ofthe wastewater sample (sample Iz-9 in Table 1) revealedthat the concentrations for all water quality parameterswere extremely high compared to typical untreated domes-tic wastewater. For example the sulfate concentration was1734 mg/l, whereas the upper bound for typical wastewateris about 50 mg/l (Corbitt, 1990). Similarly, chloride wasquantified as 10397 mg/l, which is significantly above thetypical value of 100 mg/l (Corbitt, 1990) for domestic waste-water. Metal concentrations were also beyond the upperlimits of typical untreated wastewater. These results impliedthat the fluid that remained in the quarry pits for a longperiod of time and was highly concentrated probably dueto evaporation.

The analyses results for the groundwater samples arealso presented in Table 1. The results are shown in theform of a Piper diagram in Figure 5 and a Schoeller’s semilogarithmic diagram in Figure 6. According to Figure 5, thewaters in the study area were predominantly of calcium-bicarbonate type. It can be seen from the Schoeller’s semi

Fig. 4. Conceptual cross-section diagrams and some photos of the related quarries (not to scale) (Please refer to Figure 3 for the locationsof these cross-sections).


logarithmic diagram, the groundwater samples taken fromIz-11, Iz-3 and Iz-1 have similar chemical characteristics(Fig. 6). All samples were neutral and pH values rangedfrom 6.8 to 8.7. It is evident from the analyses results thatthe ionic composition and the EC values for all sampleswere within the typical range of natural waters. It can benoted that samples from Iz-1, Iz-2, Iz-3 and Iz-11 have rel-

atively higher EC values and concentrations of ions, in par-ticular chloride, sodium and magnesium. Sampling locationsthat were close to and downstream of the waste sites exhib-ited clearly higher concentrations, e.g., Iz-11 close to site Cand Iz-1, Iz-2 and Iz-3 close to sites A and B. The hardnessof the groundwater was remarkably high; the average hard-ness throughout the study area was 310 mg CaCO3/L.

Table 1. Water chemistry in the study area

Well No. X Y Z(m) pH Eh

EC T Na K Mg Ca CI NO3 SO4 HCO3 Al As B Cd Co Cr Cu Fe Li Mn Pb Se ZnTotal hardness(mg CaCO3/L)µS/

cm °C mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L

Iz-1 732014 4481244 169 7.00 –6 1785 16.2 50.00 8.00 67.72 159.81 352.82 7.65 109.81 341.60 4 11.1 26 1.59 37.11 <.5 4.8 141 53.9 870.4 6.4 3.7 1515.6 677.3Iz-2 731393 4480775 95 7.13 –10 1222 24.14 8.00 13.75 122.89 157.02 11.89 22.03 390.40 38 1.9 19 <.05 0.15 1.8 1.8 243 4.2 8.9 7.8 0.9 6.7 363.2Iz-3 731399 4480993 95 7.11 12 1410 11.8 81.35 8.00 12.94 124.28 240.97 9.29 24.15 422.10 1 3.2 25 <.05 0.05 7.1 0.5 <10 7.1 3.13 <.1 0.8 1 363.3Iz-4 731280 4480935 94 6.80 718 8.2 15.48 4.00 9.48 93.06 33.06 15.32 24.81 402.60 <1 1.1 19 <.05 0.04 9.3 0.4 30 3.4 2.13 <.1 0.8 0.8 271.2Iz-5 731623 4480859 96 6.85 847.6 9.3 11.64 4.00 8.25 104.04 20.71 14.41 31.63 448.90 3 0.7 21 <.05 0.02 1.7 1.5 75 2.6 0.88 17.1 0.8 1.5 293.5Iz-6 731898 4480184 96 6.95 7 780 12.9 10.51 4.00 8.29 95.04 13.62 13.74 26.64 414.80 168 0.5 23 0.06 0.88 2.9 4.8 2814 2.7 36.65 13.7 0.5 446.7 271.2Iz-7 731879 4479993 97 7.11 –21 755 16.01 9.69 4.00 8.35 98.31 13.43 13.41 26.84 424.50 2 <.5 19 <.05 0.06 2.5 0.6 85 2.5 8.62 <.1 0.5 67.1 179.6Iz-8 731966 4479707 7.05 1055 17.6 10.79 8.00 9.74 95.97 13.94 13.20 26.52 434.30 2322 2 26 1.98 6.81 36.8 176.8 6712 4.8 173.99 658.3 1 46699.3 279.5Iz-9 732204 4480089 113 8.52 –67 27000 3260.76903.61 389.28 594.78 10396.65 166.90 1734.47 805.20 117 64.7 22772 1.11 31.49 11.5 239.9 515 447.7 5084.94 11.2 35.3 482.6 3085.3Iz-10 731933 4480676 95 6.98 11 1613 16.6 31.31 14.00 14.52 28.73 26.49 17.77 36.90 292.80 40 2.6 132 0.64 1.76 2.3 31.5 319 7.6 589.79 41.8 0.5 18623.4 131.4Iz-11 733367 4482177 7.00 –25 1700 14 184.76 10.21 6.00 99.78 347.42 6.53 21.97 434.30 <1 2 28 <.05 0.02 10.4 0.4 <10 10.1 0.12 <.1 0.6 1.4 273.6Iz-12 730372 4479635 8.68 –79 1108 4.7 124.31 11.29 62.18 11.73 82.52 <1.50 33.05 978.20 4 17.6 256 <.05 0.05 26.4 0.8 <10 2.6 <.05 11.3 1.2 1.3 285

ITASHY(2005)

≥6.5 and ≤9.5 2500 200 12 50 200 250 45 250 200 10 1000 5 2000 200 50 10 10

Fig. 5. Piper diagram for waters.


From the viewpoint of dissolved heavy metal concentra-tions the quality of groundwater appears to be affected bythe upstream waste sites. The most problematic water qual-ity parameters with respect to potable water quality stan-dards were iron, manganese, lead and zinc. For exampleiron concentrations up to 6712 µg/l were detected at sam-pling location Iz-8. The maximum detected manganeseconcentration was 870 µg/l at sampling location Iz-1. These

concentrations clearly did not meet the Turkish potablewater standards (ITASHY, 2005), which are 200 and 50 µg/lfor iron and manganese, respectively.

The lithium concentration was also unusually high forIz-1. Lead concentrations ranged from non-detected to 658µg/l at Iz-8. The lead concentrations exceed the water qualitylimit of 10 µg/l at three other sampling locations, namelyIz-5, Iz-6 and Iz-10. The groundwater was also sporadi-cally contaminated by zinc, with concentration reaching upto 46700 µg/l at sampling location Iz-8. In general, clearpatterns of contamination could not be detected, however itappeared that the most contaminated groundwater wassampled at Iz-8, which is located about 2 km downstreamof the solid waste disposal site (waste site D). The lakewater (sample Iz-12) was contaminated by lead, as the con-centration was 11.3 µg/l, slightly above the potable waterlimit of 10 µg/l. Chromium concentration of the lake waterwas relatively high (26.4 µg/l ) but below the potable waterlimit of 50 µg/l. It can be further generalized that highmanganese concentrations were found in wells downstreamof waste sites A and B, where concentrated wastewaterwas present, and that high iron, lead and zinc concentra-tions were detected downstream of the solid waste disposalsite. In order to present some important ions such as Na, Kand CI, a pie diagram is prepared on the map as shown in Fig-ure 7. It can be seen from the figure that the high CI values aremainly observed around waste disposal site A, B and C.

Boron in groundwater is generally low and it can be an

Fig. 6. Schoeller’s semi logarithmic diagram for waters.

Fig. 7. Na, K and CI pie diagram for groundwater samples.


indicator element to assess the groundwater pollution. Theboron levels in wastewater were measured to be 22772 µg/l.When compared the potable water standards the wastewater has very high boron content (ITASHY, 2005), whichcould potentially create groundwater pollution, particularlyin karst terrain where groundwater flow is rapid.

4.3. Karst Protection Strategies

Contaminant transport mechanism in karst aquifer isextremely fast and differs from other aquifers. Due to theabsence of protection cover soil on karstic aquifer, theinfiltration from the surface is fast and groundwater veloc-ity is higher than the alluvial aquifer. In addition, there isno contaminant retardation such as fine grained soil mate-rial in karstic feature when compared to granular aquifer.The contaminant in the granular aquifer moves slowly dueto contaminant retardation mechanisms such as chemicalreaction, ion exchange and filtration. According to hydro-geological, chemical and geological studies, the liquidwaste flow in marble unit is transported as conduit flowregime from NE to SW. When the groundwater reaches thealluvium aquifer, it starts to flow slowly and the contam-inated groundwater is exposed to some retardation mech-anism. Therefore, some chemical indicators (nitrate, chloride)are detected near drinking water standards except Iz-1which was drilled near waste site B on karstic aquifer andIz-11 which was drilled in front of karstic aquifer flow sys-tem. Iz-11 was originally used as drinking and irrigationwater purposes but it is not used for irrigation and drinkingpurposes due to high salinity for a long time. Nowadays,this well is again used for local water demand since thewaste disposal activities ceased and well electrical conduc-tivity value fall below 2000 µS/cm. This phenomenon showsthat the waste flow in karst aquifer move fast and mix withgroundwater in alluvial aquifer.

In general, the karstic feature such as dolines, shallowhole and sinkhole should be protected from waste disposalactivities due to the fast infiltration from this water flowway (Kacaroglu, 1999). This rock type is not suitable forlandfill site construction as well as sewage disposal. In thestudy area, some geo-environmental problems are deter-mined related to waste activities in or on marble rock.Especially, groundwater may be contaminated as a result ofthese waste disposal activities and groundwater qualityproblems may arise with regards to domestic and irriga-tional usage. Therefore, a groundwater management pro-gram and protection strategy of the aquifer should beprepared. To protect the groundwater, the sewage disposedto the quarries should be removed and be isolated bycement grouting. Disposing of solid waste on marble shouldbe ceased and a new solid waste site on impermeable schistunit should be searched for. Leakage from the exiting solidwaste dump should be controlled and the solid waste sur-

face should also be covered by impermeable clay barrier toavoid rainfall infiltration into the existing waste. In addi-tion to scientific and technical measures, public awarenessis very important for karst groundwater protection (Ekmekciand Gunay, 1997).

5. CONCLUSION AND RECOMMENDATION

In this study, the influence of waste disposal on karsticaquifer system is assessed via water quality monitoring.According to field studies, two aquifer systems were deter-mined: i) a highly fractured karstic aquifer and ii) an allu-vial aquifer that partly overlies the karstic system. Theslopes of the fracture zone in karst formation are very high(near vertical) with a general direction of NE-SW. It is con-sidered that this fractural pattern and its direction controlthe direction of groundwater flow, which occurs as a con-duit regime and connects to the alluvial aquifer. The allu-vial aquifer is the main aquifer system that consists ofgranular material and supplies most of the groundwater inIznik region. The liquid wastes that were discharged inthree ancient quarries and solid wastes that were dumpedon the karst terrain without any precaution measurementhave the likelihood to influence the groundwater quality inthis region.

With respect to chemical composition, water from thewastes were dark brown with high dissolved solids, andcontained some toxic elements such as As, Fe, Mn, and Zn.Leachate seepage was near neutral with high metal content.The groundwater chemistry shows that some sample loca-tions were effected from the waste deposited in the area.Especially, high Na and Cl concentrations are derived fromthe mixing of leachate seepage with groundwater. Chem-ical analyses show that some groundwater wells (Iz-1 andIz-8) are to some extent enriched in a number of elementssuch as Fe and Mn, depending on the level of mixing ofthe leachate with the groundwater.

In order to protect the karstic aquifer, some precautionmeasurement must be taken. Firstly, this aquifer rocks shouldbe protected from all waste disposal activities. Besides, someprotection zones must be determined based on detailedinvestigation of site hydrogeology, with particular focus onkarstic features such as dolines, shallow holes and sink-holes.

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Manuscript received May 31, 2010Manuscript accepted May 21, 2011

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