He has a deep interest in heraldry.

He is an expert in volcanology, studying volcanoes around the world.

He is an expert in acoustics.

I am majoring in nutrition science at university.

He is majoring in climatology at university.

He is an expert in limnology, and his research is highly regarded worldwide.

Demography is a part of social science that studies the structure, evolution, and problems of human population.

He is an expert in ornithology, studying types of birds all over the world.

He has a deep interest in etymology.

Do you remember where I put my study guide?