Why Did China’s Yangtze River Suddenly Turn Red? (Photos)
China’s historical river, Yangtze, turned red and a lot of people started to ask the cause of it. It started on September 6, 2012 when residents in the city of Chongqing noticed a spreading stain of red which immediately caught their attention. Some even got a sample of it and put them in bottles to save it.
There are several reasons why a sea or river turns to red. Last month, we reported a lake in France which turned red due to high concentration of salt. Experts say that it is caused by a salt-loving algae called Dunaliella Salina which produces a red pigment that absorbs and uses the energy of sunlight to create more energy.
Another possible reason is red tide which occurs when there’s an algal bloom, an event in which fresh water algae accumulate rapidly in the water column and results in discoloration of the surface water. However, Emily Stanley, a professor of limnology at the University of Wisconsin, said that is it unlikely that red tide is the culprit.
“When water turns red, the thing a lot of people think of first is red tide. But the algae that causes red tide is a marine group and not a freshwater group, so it’s highly, highly unlikely that this is a red-tide-related phenomenon,” she said.
After ruling out natural phenomenons related to algae, the next possible reason is through pollutant phenomenon. In recent years, due to the industrial developments in its nearby cities, the river has suffered from industrial pollution, agricultural run-off, siltation, and loss of wetland and lakes, which exacerbates seasonal flooding.
“It looks like a pollutant phenomenon. Water bodies that have turned red very fast in the past have happened because people have dumped dyes into them,” Stanley said after ruling out natural phenomenon causes.
A more specific pollutant phenomenon is siltation where increased concentration of suspended sediments accumulated on the bottom of the river. It is most often caused by soil erosion or sediment spill from deposition to get rid of unwanted material usually from barges.
“China is well known for having areas with a lot of steep hill sides and a lot of land use practices that promote soil erosion and soil going into rivers. You can get red-colored clays that wouldn’t be a whole lot different from having a big dose of dye go in there. But if that’s the cause I’d imagine there would have had to be a huge storm or a huge amount of clay go into the system,” Stanley continued.
Currently, officials are reportedly investigating the cause of it.