ICOCEE – CAPPADOCIA 2017 Nevsehir, TURKEY, May 8 - 10, 2017
Assessing the water quality and eutrophication of the Tersakan stream (Samsun-Amasya, Turkey) using water quality index (WQI) method Faruk Maraşlıoğlu*1, Hamdi Öbekcan2 1,2
Department of Environmental Protection Technologies, Vocational School of Technical Sciences, Hitit University, Çorum, Turkey (E-mail:
[email protected],
[email protected])
ABSTRACT
Water quality is an important factor for health and safety issues associated with public health and also for aquatic life. More and more water quality issues are becoming a significant concern due to the growth of population, urban expansion and development. Thus, assessment of surface water quality has become an important issue. Water Quality Index (WQI) is a single number which can be calculated easily and used for overall description of the quality of water bodies used for different purposes. In this study, the water quality data obtained from 4 sampling stations during six year between 2003 and 2009 monitoring period at Tersakan stream was evaluated. Tersakan stream is the most important water source of Yedikır Lake, an irrigation dam, in the region. It was found that NO2N, BOD5, COD and o-PO4-P values which exceed the limit values, especially at station 3 and 4, given in the water quality standards are the major pollutants that affect the water quality in the stream. During our study, the changes in dissolved oxygen of the Tersakan stream stayed within the normal limits of seasons. For easy interpretation of the data, WQI model was applied with the six selected parameters. The resulted WQI shows that 87.1, 85.2, 40.6 and 54.3 for sites St1, St2, St3 and St4 respectively. Among stations, there was significant variations in water quality index from very poor quality to fair quality that the water after exiting from Suluova and merging with Gümüşsuyu stream showed high level of deterioration at St3 and St4. The reason of the excessive pollution in these two stations is the pouring of domestic, industrial, agricultural and especially cattle farming wastes intensely into the stream after Suluova and Gümüşhacıköy districts. The most effective water quality parameters are BOD5, COD, NO2N and o-PO4-P on the determination of WQI for the present study. The results clearly show that Water Quality index (WQI) was useful tool to obtain the right decision and evaluating water quality. In future, WQI index base on the microbiological and some physico-chemical parameters can be easily used with indicator algal organisms to evaluate or to monitor water quality of aquatic body. Keywords: Physicochemical parameters; Samsun; Tersakan Stream; Water quality index. 3052
1. INTRODUCTION Water quality is a major concern all around the world, as water uses are threatened by generalized contamination resulting from human activities. The use of water quality indices (WQI) is a simple practice for assessing the water quality status, studying the controlling processes of water pollution, defining and applying environmental objectives to restore or improve water quality, assessing the effects of best management practices in a watershed and calibrating hydraulically and water quality models. A general water quality index (WQI) can be used to indicate the overall water quality conditions. It assigns a number to a body of water to indicate its quality. It consists of water quality variables, such as dissolved oxygen (DO), conductivity, turbidity, total phosphorus, and fecal coliform, each of which has specific impacts to uses [1]. So, water quality indices are intended to provide a simple and understandable tool for managers and decision makers on the quality and possible uses of a given water body. The first WQI was developed in the United States and applied in Europe since 1970s, initially in the United Kingdom. The WQI approach has many variations in the literature and comparative evaluations have been undertaken [2].
There are several water quality indices that have been developed to evaluate water quality in United States and in Canada. All of these indices have eight or more water quality variables. However, tracking and testing too many parameters is not very practical and economical. Quality criteria obtained by using a few of the most predominant or easily measurable parameters also can be reported. For this purpose, temperature, pH, dissolved oxygen, total suspended solids, and electrical conductivity were selected among the previously mentioned 15 parameters and new WQI is called as WQImin. While selecting these five parameters to use in our developed WQImin, common water quality parameters important in drinking water were mainly concentrated. Practicality of measurement was the key factor behind our decision. Specified parameters for developing WQImin can be measured easily using multiparameter water quality sondes and compact handheld instruments. Several types of these equipments are accredited and they are widely used throughout the world and they have reasonable prices for an institute. By using these equipments, aforementioned five parameters of WQImin do not need any sampling, or transportation of samples from research field to the laboratory for an extra testing using additional chemicals and equipments is not necessary.
The lake of the research area is faced with a historical threat of eutrophication. In order to decrease the cost of measures, there may be a reduction in the number of parameters observed. Since eutrophication threat exists, eutrophication parameters would have the priority among all pollution parameters. Six parameters commonly measured for the eutrophication analysis are DO, o-PO4-P, NO3-N, NO2-N, BOD5, and COD [3, 4]. Hence, it should be ascertained whether these few parameters are sufficient to give a clue about the water quality of the water body by looking correlation between WQIeut and the Modified WQI. For this purpose, a new index was created by Akkoyunlu and Akiner [5] using the above-mentioned six parameters. This index is 3053
called “WQIeut” (eutrophication) since the eutrophication parameters were used to build it up. Akkoyunlu and Akiner [5] was also used regression analysis to show the relation between fifteen-parameter WQI and other modified indices, WQImin and WQIeut.
Tersakan Stream, which is born from Akdağ in Ladik district of Amasya and merged with the Gümüşsuyu stream in Gümüşhacıköy district of Amasya forms one of Yeşilırmak subbasins. Tersakan Basin is within the borders of Amasya and Samsun provinces. Also, Yedikır Dam located in Suluova district is fed with water from Tersakan stream. Ladik, Havza, Suluova, Merzifon and Gümüşhacıköy districts are located in Tersakan basin.
Due to the intensive irrigation made with the water of the stream in the summer months, Tersakan stream almost reaches the drying point in July-October period between the junction point of the SHW Suluova regulator and Gümüşsuyu stream, and flows almost completely domestic/industrial wastewaters with water-shovelled bovine wastes. Wastes from livestock stalls at different sizes located dispersedly in Amasya-Suluova region and its surroundings of the Yeşilırmak Basin are used irregularly in agricultural areas, and its excess is discharged to the Tersakan Stream. For this reason, the Tersakan Stream is becoming a typical open wastewater channel due to intense pollution within the Suluova borders.
Tersakan Basin has also several industrial facilities that are a major source of pollutants. These are municipal slaughterhouse and oil factory located in Merzifon district, and Amasya Sugar Factory, Meat Products Processing Plant and Municipal Slaughterhouse in Suluova district. Besides, there are Organized Industrial Sites in both districts, but there is no activities in the Suluova Organized Industrial Site. There are also small industrial sites in the Ladik and Basin districts. Merzifon, Suluova, Ladik, Havza, Gümüşhacıköy districts and Amasya center have not yet WTFs (wastewater treatment facilities) in the years when the study was done. So, the domestic wastewaters in these settlements were being discharged direct or indirectly into the stream without refining [6, 7].
The objectives of this research were to evaluate spatial and seasonal trends in water discharge, nutrients and also to compare data with water quality criteria and with certain quality indices such as water quality index minumum (WQImin) and water quality index eutrophication (WQIeut), identifying the environmental pressures and assessing the impact of the loads to Tersakan basin. Human activity has an enormous influence on the global cycling of nutrients due to extensive use of inorganic fertilizers, and this direct impact is reflected to Tersakan Stream water quality as well. So, environmental quality indicators and indices are a powerful tool for processing, analyzing and conveying raw environmental information to decisionmakers and managers.
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2. MATERIALS AND METHODS
2.1. Description of the study area Tersakan Stream originated from Lake Ladik in the east of Ladik district (Samsun). The stream merges with Gümüşsuyu in Suluova, going to first the west and then to the south and ultimately, the stream poured into the Yeşilırmak River, at the exit of the city center of Amasya, near the Kunç Bridge. Tersakan Stream, 100 km long, is second class in terms of salinity and first class in terms of alkalinity when it is classified as irrigation water. The lands and valleys where pass through Tersakan Stream are similar to areas where pass through Yeşilırmak River. Anyway, Tersakan stream is located in the Yeşilırmak basin. The study area has a transition climate between the Black Sea and Central Anatolia [8].
In an attempt to continue to the proposed aims of this study, four sites were chosen for sample collection in the study area from the source region to the location where the stream merged with Yeşilırmak river (Figure 1). Water Pollution Map of Yeşilırmak Basin and its headwaters prepared by Amasya special provincial administration is also given in the Figure 2 [9]. The locations of the sampling station are as follows:
1st station (St1): The location is about 300 m ahead of the SHW (State Hydraulic Works) covers, which is the exit point of Ladik lake. 2nd station (St2): It is next to the flour plant at the 6th km of the Havza-Merzifon highway. 3rd station (St3): It is at 5 km west from junction of Yedikır Dam and under the bridge which is across the slaughter house in Suluova. 4th station (St4): The point where Tersakan stream merged with Yeşilrmak river.
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Figure 1. Map of Tersakan Basin and locations of sampling stations
Figure 2. Water Pollution Map of Yeşilırmak Basin and its headwaters 2.2. Sampling and sample analysis Water samples were taken monthly from four sites starting in 2003 until 2009. Samples were collected at 30 cm depth from the surface: All measurements were carried out in triplicate, and the results were expressed as averages. The measurement at sampling site, Dissolved oxygen, Electric conductivity, pH and water temperature were recorded. The water samples were held
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in ice boxes and immediately transported to laboratory of Ondokuz Mayıs University for water analysis following common protocols.
Electrical conductivity (EC), pH, temperature (T) and dissolved oxygen (DO) were measured locally by field instruments (WTW 340i Multi-Parameter). Ammonia nitrogen (NH4-N), nitrite nitrogen (NO2-N), nitrate nitrogen (NO3-N), orthophosphate (o-PO4) were determined using a WTW 7600 UV-Vis Spectrophotometer. Biochemical oxygen demand (BOD5) was determined by five days incubation and chemical oxygen demand (COD) with open reflux method. Gravimetric method was used to determine the total suspended solids in the water. All of the water quality parameters were analyzed according to Standard Methods for the Examination of Water and Wastewater [10, 11].
2.3. Water Quality Index (WQImin and WQIeut) Six parameters (DO, o-PO4-P, NO3-N, NO2-N, BOD5, COD) were named as the eutrophication parameters and used to obtain a new modified WQI that is called WQIeut. See Table 1 for the weighting and normalization factors used in WQIeut calculations. Linear relation was observed between WQI and WQIeut (see Eq. (1)). WQI is the modified index that uses 15 chemistry parameters, however WQIeut is another modified index that is developed considering aforementioned six eutrophication parameters. Eq. (1) shows nothing but the correlation between WQI and WQIeut. This correlation should be strong in order to say that WQIeut is reliable [5].
WQI = 0.6931 (WQIeut) + 27.547 (R2 = 0.8835, p7
>6.5
>6
>5
>4
>3.5
>3
>2
≥1
