Deat student, we can say that
Receptor is amedium which accepts pollutants. For example Human beings, plants are the example of receptor.
We may also say that the medium which is affected by pollutant is known as receptor.
In a similar way, we can say that aSink is amedium which retains and interacts with long live pollutants. A marbal wall will act as a sink for atmospheric sulphuric acid and ultimately get damage.