On September 7, an article by Daily Mail Online (UK) revealed images of the Yangtze River turning bright red near Chongqing, China ("The river that Did run red: Residents of Chinese city left baffled after Yangtze turns scarlet"). Slashdot readers, a popular geek blog site, were quick to notice that several images had bleeding artifacts indicating Photoshopped and manipulated colors.
The source of these alarming images, Barcroft Media, is a London-based media firm specializing in "the amazing side of life." Indeed, Barcroft Media's own company profile states: "As a result, our work is on time, and always to brief. What matters is that our clients receive exactly what they want, when they want it." In the case of the Yangtze River, this has caused widespread alarm. The following photograph shows the allegedly manipulated image.
Independent sightings of the unusual red color of the Yangtze River continue to circulate the internet. On September 8, a YouTube video ("China Hit With Deadly Earthquakes, Yangtze River Mysteriously Turns Red") revealed an unedited video of a particularly red river, and suggested a link to major earthquakes in the Yiliang region a few days earlier.
Is it possible earthquakes turned the river red? Could it be algae bloom (red tide)? Or perhaps industrial pollution? Official reports from the Chinese government have stated that the cause is "silt" from upstream sources.
Figure 1. Color map of the Yangtze River from Yongshan to Xiaoting
Using Google Maps, I produced the above infographic that shows the color of the river at several points along its length. The colors are unedited from the original Google images, and do not correct for color variations in the source data. Despite this, the map reveals that overall the Yangtze River changes color many times as it flows east. Each time it passes an industrial site, it turns red or brown. Between cities, tributaries along its length dilute the red and turn it back to bluish (see inset photos). At every point where two rivers meet, such as Chongqing, there is a unique mixing boundary as fresh water enters polluted water.
The current color of the river from the YouTube video mentioned earlier is also shown for Sept 8 (lower circle at Chongqing) While this color is distinctly redder than its normal brown -- enough to cause people to notice -- we also see that it is within the range of industrial pollution overall. The color used in the images by Barcroft Media is also shown (bottom left).
Yiliang county, the site of last week's 5.6 magnitude earthquake, is upstream of the Guanhe River (top left on the map). While silt from disturbed earth could cause some additional red color, it is clear that overall color variations are much greater due to industrial pollution alone. The amount of runoff at Yinjin is probably not sufficient to cause the redder color at Chongqing. Scientists have already discounted red tide as it is a marine, salt water, event which only occurs near oceans.
The degree of pollution, while not directly measured here, is a major concern. What is the river's effect on wildlife and people? In the United States, the Clean Water Act makes it illegal to discharge any stormwater runoff associated with industrial activity. In other words, it is unlawful to have any amount of water flow directly from an industrial site into a river or lake, as it must be filtered first or collected in pools. Direct verification of the Yangtze River cause would be ideal, by traveling up river until the color returns to blue, to identify the true source of the pollution. However, it is also possible that several sites upstream contribute to its color.
In current media sources and blogs, references to Biblical scenarios are prolific. To these articles and readers, I would ask the following: Do these end-of-the-world scenarios still hold true in a country which is self-reported as 60% atheist, 10% Buddhist and only 2% Christian?
Ultimately, the particularly reddish color of the Yangtze River at Chongqing is still a mystery. A mystery is an interesting thing. One can speculate widely about its cause, or one can investigate further until some truth is revealed.
Update by the author: Barcroft Media has stated that it did not modify the images received from ChinaFotoPress. The source of these color manipulations is still unexplained, and no other independent photographs have yet surfaced which show the Yangtze river with this degree of color saturation.
Editor's Note: This post has been updated to remove reference to an image of a supposedly pregnant child.
Response from Barcroft Media: Barcroft Media distributed images of the Yangtze river to clients which were supplied to us by ChinaFotoPress. The same images were also distributed by Getty Images. ... Barcroft Media's staff are committed to providing genuine and important editorial content to clients across the globe. Judging the actual colour of the Yangtze river by comparing undated, manipulated satelite imagery from Google Earth with the images distributed by Barcroft Media is scientifically flawed.