Aerial photo taken on April 13, 2021 shows the view of a salt pond at Changlu Hangu salt fields in north China's Tianjin Municipality. (Photos: Xinhua/Li Ran)

Aerial photo taken on April 13, 2021 shows an excavator working in a salt pond at Changlu Hangu salt fields in north China's Tianjin Municipality.

An excavator works in a salt pond at Changlu Hangu salt fields in north China's Tianjin Municipality, April 13, 2021.

Aerial photo taken on April 13, 2021 shows excavators working at Changlu Hangu salt fields in north China's Tianjin Municipality.

Aerial photo taken on April 13, 2021 shows excavators working at Changlu Hangu salt fields in north China's Tianjin Municipality.