Determination of seasonal water quality and pollution levels of Karasu (Araban) and Merzimen (Yavuzeli) streams

The determination of seasonal organic and inorganic pollution levels and water quality of Karasu and Merzimen Streams, important streams of Araban and Yavuzeli Provinces of Gaziantep city, used as agricultural irrigation and being under influence of agricultural activites was intended with the present investigation. With this purpose, water samplings were performed seasonally based on standard methods. The water temperature and pH level were detected in situ and collected water samples were used for determination of the physicochemical parameters of water (chemical oxygen demand (COD), biological oxygen demand (BOD), suspended solids (SS), total nitrogen (TN) and phosphorus (PO4-P), to analyse the presence and the levels of organochlorine pesticides (hexachlorobenzene, alachlor, aldrin, isodrin, alpha-chlordane, gamma-chlordane, endosulfan-I, endosulfan-II, endosulfan sulfate dieldrin, endrin, toxaphene, 4,4ˊ-DDT) and heavy metals (Pb, Cr, Ni, Cu, Zn and Fe). Among physicochemical parameters, temperature was determined to be consistent with seasonal changes, pH values presented slightly alkaline character of streams and SS values decreased in summer. The results were compared with Water Pollution Control Regulation (WPCR) to assess water quality levels. According to this, Merzimen and Karasu streams were found to be first class water quality in terms of temperature, pH, SS, COD and BOD, to be third class water quality according to TN and second class water quality when considering o-PO4 levels. The concentrations of analysed organochlorine pesticides were lower than the permissible limits prescribed by the European Commission Directive for drinking purposes and there was no statistically significant difference in pesticide concentrations between Merzimen and Karasu streams seasonally. According to recommended maximum element concentrations for irrigation purposes by United Nations Food and Agricultural Organization (FAO) Karasu Streams was considered to be suitable for irrigation meanwhile Zn content of Merzimen Stream was found to be higher than maximum recommended level. A general increasing or decreasing trend was not determined in heavy metal levels in spite of observed seasonal alterations.