Seasonal behaviour of Gediz River, as a source of particulate matter have been evaluated, by tracing the concentration of suspended solids and ultimate loads across salinity gradients in Izmir Bay. Particulate Organic Carbon (POC), Particulate Organic Nitrogen (PON), Total Particulate Phosphate (TPP), phytoplankton abundance, Suspended Particulate Matter (SPM), Particle Sizes (PS), and salinity were measured in and around the river mouth. Sorptive fractionation of nitrogen rich organic material into particles occured in the river mouth during maximum flushing period where POC:PON ratio was < 1. Principal Component Analysis (PC) indicated that the first component was PON, SPM and PS of 2-5 mu m, 5-10 mu m, 10-20 mu m related to 59% of variance, the second component was density, POC and TPP related to 17% of variance and finally 13% of variance was related to DO as the third component. PCA demonstrated that the density, among all other parameters, played the most prominent role in their variations. As a conclusion, the river mouth usually seems to be acting as a trap rather than a source for the particles carried by the river with exceptions occurring during extreme levels of flux when the river acts as a hot spot.