Here's a brief look at some of the top news stories around the world for April 3, 2015.

 In Iran, citizens celebrate nuclear agreement

The nuclear agreement between Iran and a group of world leaders was greeted mainly with optimism in the Middle Eastern country, with some celebrating the announcement in the streets. The deal could be the first major step to repairing U.S.-Iranian relations in decades.

[Read more from Reuters]

After nearly 30 years, man wrongly sent to death row is released

A man who spent nearly three decades on death row in Alabama was released Friday morning, and, while thankful for his release, said everyone who played a part in unjustly sentencing him "will answer to God." New technology related to firearms evidence led to a re-trial, and his release.

[Read more from the Washington Post]

The byproduct of technology: A giant, black lake of sludge

A reporter took a trip to Baotou, the largest industrial city in inner Mongolia, to see what the waste that comes from mining materials for smartphones and other modern gadgets looks like. The result: " ... an artificial lake filled with a black, barely-liquid, toxic sludge."

[Read more from the BBC]