INVESTIGATION OF HEAVY METAL CONCENTRATIONS IN SOIL CAUSED BY KASTAMONU CITY WILD STORAGE DUMPSITE

The aim of this study was to reveal the effects of domestic dumpsite on the some soil chemical properties in the surface soils in Kastamonu city. The soil samples were collected from the 5 different distances namely; Very adjacent (VA), Adjacent (A), Middle (M), Far (F) and Very far (VF). The results showed that the accumulation of heavy metal in the soil varied significantly with the distances. Among the heavy metals, the concentrations of Co, Cr, Cu (only A and VA), Zn (only A and VA), Ni (except for M) exceeded the Maximum Allowable Limit (MAL) for Turkey values. However, the concentrations of Mo, Pb and Cd were below the MAL limit values. When all results are considered, it can be stated that the waste dumpsites can negatively affect the environment. Therefore, we make sure that the dumped materials should be concentrated and recycled in order to decrease the amount of heavy metals in the dumpsites and in the soils around the dumpsites. In addition, phytoremediation, which is all the remediation technique available for metal contaminated soils, is the most costly, environmentally friendly and easy to apply. Phytoremediation can be used to remove, displace or reduce contaminants from soil by using plants that hyperaccumulate these contaminants.


INTRODUCTION
The municipal garbage area is one of the most common ways to dispose of urban solid wastes in the world (Xiaoli et al., 2007). Increasing human activity both industrial and domestic causes the increase of waste volume produced from time to time. Most waste is directly discharged into the environment without any intervention. As a result, pollution that harms people and nature occurs. It is the soil pollution that the chemicals enter and change in the natural soil environment (Artiningsih et al., 2018). The factors that cause toxic metal to be included in the contaminant group are due to the nondegradable and easily absorbed properties of the heavy metals (Ni, Co, Cr, Cd, Pb, Cu, Zn, Mo etc.). Tatsi & Zouboulis (2002) noted that incorrect collection, separation, and disposal applications of domestic solid waste can produce leachates containing high concentrations of ammonium, organic matter, and heavy metal. Uncontrolled storage area is very dangerous for people health and environment (Sakawi et al., 2017).
The total domestic waste disposal in Turkey is estimated to be approximately 27 million tons in 2006. Sixty-four percent (64%) of municipal waste is maintained through regular storage, 30% by wild storage (uncontrolled storage), and 6% by recycling. Thirty percent (30%) of the waste collected in municipalities is plastic, 9.7% metal, 40.7% paper and cardboard, 10.9% glass, 2% wood and 6.7% composite. According to the Turkey Statistical Institute (TÜİK 2017), the amount of municipal waste has increased from 17.76 million tons in 1994 to 31.58 million tons in 2016. According to the data of the Ministry of Environment and Urbanization in 2017, the ratio of the population served by regular storage facilities to the total municipal population is 74%. The Kastamonu Environmental Status Report has shown that 26% of urban waste is organic waste, 5% glass waste, 10% paper-cardboard, 4% plastic waste, 6% metals, 1% composites, 12% inert materials, 19% the functions smaller than 10 mm and 13% the other categories (Anonim, 2014).
The objectives of the present study were to (1) determine the concentrations of 8 heavy metal (Ni, Co, Cr, Cd, Pb, Cu, Zn and Mo) in the soils around the city dumpsite of Kastamonu (2) to investigate the effects of different distances to the dumpsite, and (3) asses the concentration and average distribution of heavy metals according to Earth Crust, Maximum Allowable Limit for Turkey (MAL) and Sedimentary-Carbonates Rocks values. Turkey has standard Regulation on Control of Soil Pollution for heavy metal concentration in the soil (Anonim 2001). Therefore, the results of this study will be compared to the Regulation on Control of Soil Pollution and Earth Crust values.

Study Area
This study was conducted in City Wild Storage Dumpsite, located in the north part of Kastamonu province,northwest Turkey (41°25'16" N,33°45'44" E). This study area was 9 km away from the city center and covered an area of approximately 70 000 m 2 and a depth of approximately 25 m (Fig. 1). The elevation was 863 m. a.s.l. and the capacity of the garbage dump was 180.000 m 3 (KASMİB, 2018).

Figure 1. Location of the Study Site
According to the geology maps by the General Directorate of Mineral Research and Exploration, the bedrock of dumpsite is mostly dominated by sedimentary rocks, medium to thick bedded, abundant jointed, gray-beige colored, massive structure, Eocene-bearing neritic limestone (Akbaş et al., 2015). The soil type presents the characteristics of brown forest soil (Anonim, 1990). The characteristics of such soils are loamy or fine-structured, high base saturation (more than 50%) and high biological activity. The soil is calcareous and the soil pH varies from 8 to 9.
The study area is characteristic to Black Sea climate with winters, warm and rainy, summer months, hot but not arid in the region. According to the weather data for 2008-2019 (Kastamonu Meteorology Station at 800 m a.s.l.), mean annual precipitation is 623.6 mm, with the highest amount in June (122.5 mm), and the lowest amount in October (24.8 mm), while mean annual temperature is 10.4 o C, with the highest month in August 20.7 o C and the lowest month in January -0.8 o C (DMİ, 2019).

Sample Collection and Analysis
Soil samples were taken from 5 different locations away from the dumping site, with the distance at least 30 m each other namely; Very adjacent (VA), Adjacent (A), Middle (M), Far (F) and Very far (VF). The area of the study is approximately 70 000 m 2 (L: 300 m and W: 250 m), but it was studied at 5 different points in a 180 m long area due to the fact that the pile of rubble in the land is excessive and has a rough terrain structure (Fig. 1). A total of 15 soil samples, with three replicate each distance, were taken from a depth of 10 cm using soil core device with an inner diameter of 5 cm. In addition, the soil samples could not be taken too much since the city dump is in group and group garbage dump (Fig. 1). The moist field samples were sieved to remove stones, roots and macrofauna and collected to give a single representative soil sample for each distance. The samples were placed into labelled polythene bags and taken to the laboratory for chemical analysis. Soils were air dried for two weeks, ground and sieved through a 2 mm sieve.
Soil pH (H2O) and heavy metal concentrations were determined. Soil pH (H2O) was measured in a 1:2.5 mixture of distilled water and soil by pH meter (LaMotte pH 5 series meter) after equilibration for 1 h in solution (Jackson, 1962). Determination of heavy metal concentration in the soils was analyzed using XRF (X-ray Fluorescence Spectrometer). Soil analyses were triplicate.

Statistical Analysis
An Analysis of variance (ANOVA) has been carried out for analyzing the effects of the distances on the soil heavy metal concentrations using the SPSS program (Version 22 for Windows). Following the results of ANOVAs, Tukey's Honestly Significant Difference (HSD) test (α=0.05) was used for multiple comparisons to examine the significant response of the heavy metal concentrations to the distances. The correlation coefficient was also used to measure the strength of inter-relationship among the heavy metals.

RESULTS AND DISCUSSION
As is known, data must fulfill two assumptions in order to apply the analysis of variance. The data should have minimum interval scale and show a normal distribution. Therefore, fitness of data to normal distribution was checked through the Shapiro-Wilk one sample test. It was found that the the majority of heavy metal concentrations demonstrated normal distribution (P>0.05) ( Table 2).

Heavy metal concentrations
The variation in mean Ni concentration with the distances in the soil is shown in Fig. 2. The Maximum Allowable Limit in Turkey (MAL) for Ni is 75 mg kg -1 (Anonim, 2001). The adjacent distance (A) had the highest Ni concentration (967.2±78.9 mg kg -1 ), whereas the middle distance (M) had the lowest Ni concentration (64.1±3.82 mg kg -1 ), which was the only Ni concentration below the MAL value in the soil. The other distances also had Ni concentration above the MAL values (Fig. 2). Najib et al. (2012) found that the concentration of Ni was 30 mg kg -1 in the Kangar dumping site. Similarly, Tumuklu et al. (2007) reported that the concentration of Ni increased with decreasing the distance to the Niğde city garbage dumpsite (460 mg kg -1 ). Olafisoye et al. (2013) reported that Ni concentration decreased from the top soil (85.43±0.02 mg kg -1 at 0-15 cm) to the subsoil (35.45±0.01 mg kg -1 at 15-30 cm). In most countries, Ni concentrations were found to be over the critical value. The results in this study were in agreement with the study by Adelekan & Alawode (2011) who found Ni concentration ranging between 18 mg kg -1 and 335 mg kg -1 . Turhan et al. (2020) reported that the Ni concentrations under the agricultural surface soil samples in Kangal varied from 89.5 mg kg −1 to 971.0 mg kg −1 with an average value of 610.1 mg kg −1 .

Figure 2. Mean Ni Concentration in the Soils around the Dumpsite
Mean Co concentration was above the MAL value in the soil (Fig. 3). The highest Co concentration was found in the soil of very far (VF) distance (34.2±4.24 mg kg -1 ), whereas the lowest Co concentration was seen in in the soil of the middle (M) distance (26.1±4.03 mg kg -1 ). The lower concentration of Co was also shown by a number of studies. For example, Lu et al. (2010) found that the concentration of Co at the street dust of Baoji was 15.9 mg kg -1 .  (Fig. 4). This result could be due to the lower Cd concentration in the wastes in the dump site. Uba et al. (2008) stated that cadmium had the highest level bioavailability in the dumpsites. In general, the higher concentrations of Cd in a dumpsite may be attributed to various sources, some of which include automobile tire dust, burning of oil and tyre, plastic wrappings, paints, dyes, and especially, refuse dumps and commercial activities (Ali et al., 2005). Sulaiman et al. (2018) reported that the concentration of Cd in soil samples of two dumpsites (A and B) varied from 2.20 mg kg -1 to 1.53 mg kg -1 . They argued that this variation in Cd concentration may depend on the types and the compositions of waste at the dumpsites. Asemave & Anhwange (2012) stated that anthropogenic release of Cd under soils might be as a result to the increase in disposal of Cd containing substances such as batteries in phones and torches, plastics and other electronic gadgets, to the municipal waste dumpsite. Jafaru et al. (2015) found that the Cd concentration was higher than 0.73 mg kg -1 in a dumpsite soil in Ghana. Adaikpoh (2013) noted that the average Cd concentration in the dumpsites was 1.18 mg kg -1 and ranged from <0.001 -2.30 mg kg -1 in Imoru. Asemave & Anhwange (2012) noted that cadmium uptake was high in acids soils and was reduced when the soil was limed. In the present study, the soil pH was generally alkaline, and this could be the reason that Cd concentrations were lower in the soil samples of all distances. The average concentration of Pb in the soils of the dumpsite from all distances showed the lowest concentrations compared to the MAL value (300 mg kg -1 ) (Fig. 6). Among the different distances, the Pb concentrations were higher from the adjacent (66.3±4.67 mg kg -1 ) and the very adjacent distances (55.6±3.75 mg kg -1 ) than the soils from the middle, the far and the very far distances (Fig. 6). Ebong et al. (2008) reported that the concentration of Pb at the dumpsites ranged from 9.46 mg kg -1 to 18.83 mg kg -1 compared to the control sites which ranged from 5.21 mg kg -1 to 7.53 mg kg -1 . However, Peramaki & Decker (2000) found that the concentration of Pb varied between 8.0 mg kg -1 to 1185 mg kg -1 which were clearly exceeded the MAL limit value. The higher values in Pb concentrations were also shown by Kanmani & Grandhimathi (2013), ranging from 44.09 mg kg -1 to 178.84 mg kg -1 . Madhaven et al. (1989) have stated that Pb is liable to accumulate in the top soil. They have emphasized that if any city is less populated, it creates little wastes in the dumping sites and consequently it may result in lower Pb concentrations in the soils around the dumpsite. The soils from the adjacent and very adjacent distances had higher Cu concentrations compared to the other distances (Fig. 7). The values of Cu concentrations from the adjacent (636.5±50.61 mg kg -1 ) and very adjacent (493.1±50.4 mg kg -1 ) distances clearly exceeded the MAL values (140 mg kg -1 ). Ebong et al. (2008) found lower concentration of Cu under soils ranged from 2 to100) mg kg -1 . According to Dara (1993), the higher concentration of Cu at the dumpsite might be connected to biodegradable waste releasing the metallic Cu into the soil. This can be due to the incorrect disposal of waste lubricants, as well as waste containing electrical and electronic components (Nwachukwu et al., 2011). When the Cu concentration enters the soil, it usually adheres strongly to organic substances and minerals (Jaradat et al., 2005). As a result, it doesn't go very far after releasing (Adriano, 1986). Perhaps this situation can explain why the higher Cu content recorded in the soil near the dumpsite than the further away from the dumpsite in this present study. The concentrations of Zn in top soil of the adjacent (422.9±4.60 mg kg -1 ) and the very adjacent distances (760±24.32 mg kg -1 ) were higher than the other distances (Fig. 8). The higher concentrations of the adjacent and the very adjacent distances were also over the limit value of the MAL for Zn in the soil (300 mg kg -1 ). The other distances, however, showed much lower values than the MAL value. Asemave & Anhwange (2012) also found lower Zn concentration in the soils ranging between 13.82 mg kg -1 to 17.26 mg kg -1 compared to the control sites ranging from 6.32 mg kg -1 to 8.15 mg kg -1 . However, a study by Odukoya et al. (2000) showed higher Zn concentration in the soils ranging from 100.80 mg kg -1 to 226.00 mg kg -1 . The reason for this change is due to the disposal of high content Zn waste to the landfill. Comparisons the average concentrations of heavy metal in the soils from dumpsite distances are given in Table 3. Ni, Pb, Cu, Zn and Mo concentrations are the highest value at adjacent (A) and very adjacent (VA) distances.  (Turekian & Wedepohl, 1961), the average Ni concentration is about thirteen times higher than earth's crust average of 20 mg kg -1 (Tab. 1). Similary, Turhan et al. (2020) noted that the average of Ni concentration in the agricultural ultrabasic soils were about ten times higher than the earth's crust average of 58 mg kg −1 . Cobalt (Co) concentrations were an average value of 29.37 mg kg -1 (Tab. 2). The average Co concentration was about three hundred times higher than earth's crust average of 0.1 mg kg -1 (Tab. 1). Cadmium (Cd) concentrations in the soil were an average value of 2 mg kg -1 (Tab. 2). The average Cd concentration was about fifty seven times higher than earth's crust average of 0.035 mg kg -1 (Tab. 1). Chrome (Cr) concentrations in the soil were an average value of 122.71 mg kg -1 (Tab. 2). The average Cr concentration was about eleven times higher than earth's crust average of 11 mg kg -1 (Tab. 1). Similary, Turhan et al. (2020) noted that the average of Cd concentration in the ultrabasic soil were about nine times higher than the earth's crust average of 83 mg kg −1 . The average lead (Pb) and molybdenum (Mo) concentrations were about four times higher than the earth's crust average of 9 mg kg −1 and 0.4 mg kg −1 , respectively (Tab. 2). Finally, copper (Cu) and zinc (Zn) concentrations were approximately sixty four times and fourteen times higher than the earth's crust average of 4 mg kg −1 and 20 mg kg −1 , respectively (Tab. 1).

Correlation Coefficient Analysis
Correlation coefficients of Pearson for the heavy metals in the wild storage dumpsite of Kastamonu city are shown in Table 4.  Liu et al. (2013) noted that all heavy metals (except for Pb) relatively low concentrations from 0.1 to 1 km from the dumpsite. Therefore, they are much lower than that found in the soils in the dumpsite in other countries including Turkey. In this present study, we found serious accumulation of heavy metal except for Cd, Pb and Mo in relation to the different distances. Tumuklu et al. (2007) showed that the heavy metal concentrations in study area soils diminished with distance to the dumpsite. In our study, Cd and Pb concentrations regularly showed a decreasing trend with the distance to the dumpsite (p<0.05). However, Cu, Zn and Cr concentrations did not show same trends (Table 4). This result has indicated that the enrichment of Cd and Pb concentrations can be caused by the dumpsite. It is due to the fact that Cd concentration has the highest mobility and is more susceptible to release than Zn, Cu, Cr or Pb concentrations (Xiao et al., 2005;Prechthai et al., 2008;Liu et al., 2013). In study area, the strong correlation between these heavy metals can be said to increase the contaminants which originates from anthropogenic (Tumuklu et al., 2007).

CONCLUSIONS
The study has indicated that the concentrations of eight heavy metal (Ni, Co, Cd, Cr, Pb, Cu, Zn and Mo) in the soils around dumpsite in Kastamonu vary significantly with the distances to the dumpsite. Except for Cd, Pb and Mo concentrations, the polluted levels of Ni (except for M) Co, Cr, Cu (only A and VA), Zn (only A and VA) exceed the standards of MAL and Turkey Pollutant Standards which could result in eco-toxicological risk. In particular, the concentrations of Ni, Cu and Zn are noted to be highest. This study also clearly indicates that human activities can be a significant factor of heavy metal contamination in the soil. Consequently, phytoremediation techniques such as phytoextraction is more ideal as a method of remediating contaminated soil and water. Future studies should be focused on identify remediating plants that are adapted the local climate and soil conditions, the combined use of more than one phytoremediation approach for the successful remediation of the contaminant area under field conditions.