Substances that are broken-down by biological processes are said to be _________.
According to natural disposal, the pollutants may be biodegradable or nonbiodegradable.
1. Biodegradable pollutants: These are quickly degraded by natural means. Sewage and heat are pollutants of this category. These pollutants are disposed of by microbial action and radiation respectively.
2. Nondegradable pollutants: These are not degraded or are degraded slowly in nature. DDT, arsenic salts of heavy metals, glass or tin containers, radioactive materials, and plastics are the pollutants of this category. These pollutants accumulate and may get biologically magnified as they pass through the food chains.
So, the correct answer is 'Biodegradable'.