Question

Two mechanisms for water pollution

Answer 1

The answer is Direct and Indirect water pollution

Direct water pollution is when we throw pollutant  directly into the water ( Such as throwing out factory waste in the river, keeping nuclear waste under the sea, etc)

Indirect water pollution is when we're not directly throw the pollutant into the water, but somehow it ended up there. ( for example when we use a pesticide, the pesticide will absorbed into the soil and eventually found its way to underground water source)

Answer 2

Oil spills/boats (not all but some) That's what I can think of :)