Determination of water quality of Şahnahan Stream and Sultansuyu Stream (Malatya) using physical-chemical parameters

This thesis aimed to determine the levels of 14 physicochemical parameters (DO, WT, EC, pH, TSS, NH4-N, NO3-N, TN, PO4-P, TP, COD, SO4, Ca and Mg) and 10 metals (As, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, and Zn) in water samples seasonally collected from four sampling stations in the Şahnahan Stream and Sultansuyu Stream, which flow into the Tohma River. It also sought to evaluate the water quality of both streams using various indices. In the Şahnahan Stream, the lowest average DO levels and the highest average EC, TN, TP, PO4-P, TSS, COD and SO4 levels were recorded at station B2, located just downstream from where wastewater from the Malatya Organized Industrial Zone is discharged into the stream. In the Sultansuyu Stream, only TSS, Pb and SO4 levels showed statistically significant variations among stations (P < 0.05). It was determined that the average As, Fe, and Pb values recorded in both the Şahnahan Stream and the Sultansuyu Stream exceeded the values permitted by drinking water quality criteria. Furthermore, the average Cd and Pb concentrations in both streams were found to exceed the "continuous concentration criterion" from the freshwater criteria for the protection of aquatic life. Health risk assessment results also indicated that exposure to metals through drinking the water in both streams could pose non-carcinogenic and carcinogenic risks to humans due to the element As. The water quality indices (WQI, NPI, OPI, and RPI) used in this study revealed significant pollution in the Şahnahan Stream, particularly at station B2, with the exception of station B1. In contrast, the sampling stations of the Sultansuyu Stream were generally determined to have high water quality.