The global demand for a wide variety of applications based on engineered nanoparticles (ENPs)has expanded the worldwide industrial scale production and inevitably released these materials into the environment. The increasing existence of NPs and its impact towards human health and the environment especially the aquatic system has sparked a great concern among both the scientific community and the public. It is therefore crucial to gain an in depth understanding of the properties the manufactured nanoparticles possess along with the various transformations they undergo that determine their behaviour and mobility. This review begins by addressing the fundamental physicochemical aspects of manufactured oxide nanoparticles with detailed attention given specifically to ZnO as a representative example in a separated section. The literature collected is summarized and focused on the essential point of view to evaluate their occurrence, fate and transport in the natural aquatic environment as a result of their interactions with other nanoparticles or natural colloids. Key methods and principles of nanoparticle characterization are also presented.