Mouth of the mighty Yangtze
The coloured waters shown here in this 21 March Envisat Medium Resolution Imaging Spectrometer (MERIS) image have concluded a long journey across China.
They are surging into the East China Sea from the mouth of the Yangtze River, which at 6300 km long is the longest river in Asia and the third longest in the world.
Rising in the Qinghai-Tibetan Plateau, the Yangtze River snakes through nine provinces and serves as a drain for 1.8 million square kilometres of territory. MERIS is designed to detect ocean colour, and clearly visible here is how the Yangtze's heavy sediment plume discharges into and colours the waters along the Chinese coast. Its total sediment load is estimated at 680 million tonnes a year – equivalent in weight to a hundred Great Pyramids.
Shanghai - China's largest city - is located south of the Yangtze mouth and the 1000-km-long navigable stretch of the Yangtze west of it is a zone of major economic activity. The downside of recent growth has been a decrease in water quality that the Chinese government say it intends to combat. At the start of the month an accidental chemical spill into a tributary of the Yangtze temporarily deprived almost a million people of drinking water.