Answer:
environmental monitoring
Explanation:
Environmental monitoring is referred to the basic study where all the environmental factors are studied like, land, soil, water, etc: So that the level of contaminants can be verified. This basically leads to the analyses of the concerned environment over certain period, as this is done for a period of time.
In the given instance also the event took place around 10 years ago, now environmental monitoring done will provide the details of contaminants in that environment.
