Nanomaterials describe, in principle, materials of which a single unit is sized (in at least one dimension) between 1 to 1000 nanometres (10−9 meter) but usually is 1 to 100 nm (the usual definition of nanoscale).
Shallow lakes have been greatly affected by increased concentrations of nitrogen and phosphorus from intensive agriculture and increased human populations. These key nutrients for plant growth enter the aquatic environment, changing clear water to turbid through a phenomenon called eutrophication.