Transport, fate and toxicity of the emerging and nanomaterial contaminants in aquatic ecosystems: removal by natural processes

The emerging and nanomaterial contaminants are commonly found in surface water; groundwater; lakes; rivers; wastewater treatment plant influents, effluents, and biosolids; etc. The extensive and intensive use of new consumer products, pharmaceutical products, and scientific products for human life, medicine, food production, and industrial purposes has introduced emerging and nanomaterial organic and inorganic contaminants into the environment. Some pharmaceuticals and endocrine disruptors disrupt the normal functioning of the endocrine system, normal growth, development, reproduction, and behavior of organisms. The seasonal variation of water flow, temperature, and climate has significant role on the temporal variation of emerging contaminants in aquatic ecosystems. The nanomaterial contaminants originate from carbonaceous nanomaterials, metal oxides, semiconductor materials, quantum dots, and nanopolymers. These contaminants are released to the environment through atmospheric emissions; disposal of solid or liquid waste streams from factories, hospital, and other healthcare facilities; illicit drugs; municipal sewage; municipal wastewater treatment plants; stormwater drainage; fuel combustion; etc. The engineered nanomaterials (ENM) encounter the complex fate and transport in aquatic ecosystems due to the multiple dynamic interactions between the physical/chemical properties of ENMs and complex environmental conditions. The engineered nanomaterials aggregate with other materials in water or transform to secondary products. The ENM aggregates with suspended particle matter, colloids, and DOC, deposited to stream, lake, or estuary bed with settleable suspended particle matter and then buried in sediments or resuspended in the water column depending on hydrodynamics. The ENMs are bioavailable to plants causing trophic transfer and biomagnification of plant. The nano-bio-eco interactions significantly control the nanotoxicity of nanomaterials.