снижение

см. тж. понижение

A drop in pH ...

The increase in sensitivity is not accompanied by reduced detection limits.

If helium atoms are slowed down by lowering the temperature, ...

The fall (or decline, or reduction) in (or of) resistivity ...

A decline in productivity ...

A drop in production ...

Источник: Русско-английский научно-технический словарь на Gufo.me