#A Vast - #A Growing - #A Wealth of Something - #A Multitude of Something

 A Vast / An Enormous / A Considerable / A Huge / A Tremendous Amount of +  Uncountable Nouns

Ex:

1. The final reason is that the mass production of inexpensive goods can place a heavy burden on the environment when a huge amount of exhaust emissions from factories are frequently released into the atmosphere, accelerating global climate change.
2. Admittedly, not all of the information available on the Internet is reliable or helpful as there is a vast amount of material online that some would consider offensive or dangerous, ranging from pornography to instructions on how to make bombs.

 A Growing / A Huge / A Considerable / A Substantial / An Enormous Number of + Countable Nouns

 Ex:

1. For instance, a huge number of countries offered medical assistance and other humanitarian care to Japanese people who were devastated by an earthquake and a tsunami in 2011.

2. It is true that a growing number of young people from affluent countries are doing temporary jobs without payment in less wealthy countries.

 A Wealth of Something = A Large Amount of Something

 Ex:
1. The authors have assembled a wealth of material.
2. She has gained a wealth of experience in human life.
3. Although the sarcophagus it's off limit's, ancient astronaut theorists can still find a wealth of evidence in the carvings along the walls of Palenque.

 A Multitude of Something = A Large Number of People or Things

 Ex:
1. There has suddenly appeared a multitude of banners and pamphlets.
2. I had never seen such a multitude of stars before.
3. Flowers, exquisitely perfumed and graced with a multitude of colours and shapes, bloomed in Spring.