Experts say the ability to take up lead is reduced when the pH level is above six and a half.

VOA: special.2009.06.09

The nesting grounds for pelicans, gulls and other water foul, they rise less than 30 centimeters above sea level.

VOA: standard.2010.05.09

The land surface pokes just a couple of meters on average above sea level, making it the lowest-lying nation in the world.

VOA: standard.2009.10.17

Many of the islands that make up the Maldives rise little more than one meter above sea level, and could disappear under the sea if global temperatures continue to rise.

VOA: standard.2009.11.09

It wasn't just the beauty of the polished stone block walls or the fact that this abandoned city sits atop a narrow ridge more than 2400 meters above sea level.

VOA: standard.2009.12.15