A study of ionic composition and inorganic nutrient fluxes from rivers discharging into the Cilician Basin, Eastern Mediterranean

Abstract

Present water quality of the perennial rivers; Göksu, Lamas, Efrenk, Tarsus and Seyhan discharging into the Cilician Basin have been investigated. Monthly surface samples collected from three stations downstream of the rivers during the period of October 2004-May 2005 were analyzed to determine ionic composition (Cl(-), SO(2-)(4), N(O-)(3), PO(3-)(4), N(H+)(4), Ca(2+), Mg(2+), Na(+) and K(+)), in addition to measurements of pH, electrical conductivity, alkalinity and total hardness. The results have been compared with recommended water quality standards. Excluding Göksu, Seyhan and Efrenk river mouths, values for almost all measured parameters, except N(H+)(4), were found to be lower than the desirable limits. In particular, inorganic ammonium, phosphate and nitrate concentrations for Göksu and Seyhan Deltas were 10(1) or 10(2) orders of magnitude higher than the concentrations of the rest of the samples. Temporal variation in levels, primarily observed in PO(3-)(4), suggest the impact of agricultural fertilizers intensively used around Göksu and Seyhan Rivers. According to Turkish National Water Pollution Control Regulations, all rivers were found to be unpolluted with respect to their nitrate, chloride, sulfate and sodium ion contents, while they all could be considered as slightly polluted with respect to their phosphate contents. In contrast to nitrate and phosphate, ammonium exceeded the maximum permissible limits of water quality criteria in almost all samples. Among the sampled rivers, Tarsus River was better in water quality, with the lowest electrical conductivity, alkalinity, total hardness and nutrient concentration values. Calculated values of elemental inorganic N and P fluxes suggest a substantial increase in nitrogen loads within the last decade, compared to a significant decrease in phosphorus loads of the rivers during the same period.