your fart and the other fart that's coming in July
A mineralogist studies minerals.
An ecologist studies pollution
A scientist who studies water (H2O) would be a hydrologist or a water chemist.
The kind of scientist who studies Urology would be a Biologist, since Urology concerns a biological function (urination). If you mean the kind of doctor who studies Urology, that would be a Urologist.
meteoroligists
Audiologist
An Ichthyologist.
Botanist
cosmologists
seismologist
a biologist
Mathmaticion