Slideshow

• River is "not dead"
• Absolute poison levels in water "alarmingly high"
• Ecosystem of Yangtze can be saved if China intensifies water protection

A recent survey of the water quality of the Yangtze river shows an unexpected outcome: Generally speaking, man-made pollution in the Yangtze compares globally with that of other main rivers.

"Contrary to our expectations the river is not dead," said August Pfluger, CEO of the baiji.org Foundation. "The ecosystem of the Yangtze can be saved if China intensifies its activities in water protection now." Nevertheless, there is no reason to give an all-clear signal because the absolute poison level in the water is alarmingly high. Contrary to earlier assumptions, there seems to be no direct connection between the Yangtze's chemical water quality and the baiji's disappearance.

"The water quality of the Yangtze is comparable to that of other large rivers in the world," said Beat Müller, responsible for the study and geochemist at Eawag, the Swiss Federal Institute of Aquatic Science and Technology. "The current heavy metal concentrations in the Yangtze remain about two to eight times smaller than in the Rhine 30 years ago, at the peak of its pollution."

European Union guidelines for several heavy metals are all higher than the concentrations found in the Yangtze, which shows that even today many European rivers still struggle with significantly higher pollution levels. Nevertheless, many rivers in industrialized nations are already seeing a reversal of this trend as levels of toxic pollutants are declining, while they are still increasing in China.

Nevertheless, there is no reason for an all-clear. Part of the reason for the Yangtze's lower concentrations is its huge body of water - the third largest in the world. Where the Yangtze enters the East China Sea, it transports an average of 31,900 m3 per second and the poison levels are substantial. "Each day, the Yangtze discharges about 1500 tons of nitrogen, mainly from agriculture, and 4.6 tons of arsenic into the coastal waters," said Müller. "The more nitrate enters the sea, the more the blue-green algae grow, mainly at lower sea levels, and the oxygen becomes scarce."

Although the dilution of pollutants should prevent an immediate and irreversible damaging of the ecosystem, the high levels of pollutants where the Yangtze enters the sea must have devastating effects on the coastal zone. It is here where these harmful substances accumulate with little researched consequences. The disproportionate spreading of algae and high levels of heavy metals in coastal organisms are only two examples.

Pollution from heavy metals is particularly harmful in drinking water. On its way downstream the Yangtze delivers drinking water to a dozen of cities with over a million inhabitants each and to Shanghai. It also irrigates what is considered China's breadbasket and every third fish eaten in China is caught in the Yangtze.

In autumn 2006, an international team of scientists started to track the last baiji dolphins in the Yangtze river. During their six-week survey, Eawag took water and sediment samples on the 1,750km distance between the Three Gorges Dam and Shanghai to determine the water quality.

Until recently the baiji (or Chinese river dolphin, Lipotes vexillifer), one of five types of river dolphins, was considered the most endangered cetacean species. Chinese scripts referred to it as early as 1600 years ago. But its numbers have decreased along with China's booming economic development: About 400 baijis were left in the early 1980s, but a 1997 survey only found 13 remaining individuals. The last confirmed sighting of a baiji was in September 2004. The last baiji, named QiQi and kept in captivity, died in 2002. Finally in November 2006 a joint expedition between the Swiss baiji.org foundation and the Institute of Hydrology, Wuhan, China could not track a single baiji. Instead, after a search along 3000 kilometers, the scientists had to declare the baiji "functionally extinct" - the first large cetacean to become extinct in this century.

Effects on the baiji:
The results show no direct correlation between the chemical water quality of the Yangtze and the disappearance of the baiji dolphin or the decrease of Yangtze finless porpoises to presently remaining 400. Instead, the baiji's disappearance can rather be linked to degrading conditions in its habitat, where water pollution is likely to be an additional damaging factor. Overall, the habitat of the two freshwater cetaceans has significantly changed in the last centuries: Industry and agriculture have boomed along the river and both pollute the water with their untreated wastewater. The massive increase in shipping traffic has led to higher contamination as well as collision risks. In addition, extreme underwater noise makes it nearly impossible for the sensitive baiji to orientate himself. Heavy canalization, the river's straightening and the cutting off of smaller tributaries - areas which serve as "hatchery" for many fish species - has lead to changing food supplies. The same applies to fishery and fishing methods, where it is not uncommon for larger species like the baiji to become unwanted by-catch.

Looking ahead:
China's ongoing industrialization, rising living standards, artificial irrigation, growing power generation and the envisioned large-scale export of water into the catchment area of the Yellow River in the North will put even more pressure on the Yangtze. Together with a steady increase in man-made pollution, the pressure on the river's ecosystem, especially in the coastal waters of the East China Sea, will increase further. It will also affect the quality of the ground and drinking water.
It is therefore recommended to learn from the bad experiences in Europe and to reverse the current trend as soon as possible to allow a sustainable future for the people and the environment of the river. It is too late to save the baiji, but other unique species like the finless porpoise or the Chinese sturgeon could be saved through such measures.

Notes:
About the expedition:
The "Yangtze Freshwater Dolphin Expedition" was organized by the baiji.org Foundation together with the Institute of Hydrobiology, Wuhan. Under the auspices of the Chinese Ministry of Agriculture it included scientists from six nations, amongst others members of Eawag, part of Eidgenössische Technische Hochschule (ETH).

The expedition's primary goal was to detect any remaining baiji and the equally endangered finless porpoise (Neophocaena phocaenoides asiaorientalis). Additionally, researchers took water and sediment samples every 50 to 100 kilometers. It was the first time for the Chinese government to allow foreign scientists to research the water quality of the lower Yangtze. Almost 400 million people, or seven per cent of the global population, live in the larger Yangtze basin. 

The Swiss-Chinese project was supported by the Swiss government's development organization Directory for Development and Cooperation (DEZA), the world's largest inspection and testing company SGS and Pictet. Canon, Victorinox and Katadyn further supported the project.

Results in detail:
At some places and at given times, the scientists found high (peak) concentrations of certain elements and organic compounds, but they were mostly diluted further downstream. Of the 236 organic chemicals, only a few were locally found at high levels. Many of the persistent substances used in agriculture appear only seasonal and in traces. Overall, the concentrations of several toxic pollutants such as arsenic, thallium and antimony increased downstream. The increasing use of mineral fertilizers in agriculture is also leaving its mark. The nitrogen concentration, for instance, has doubled in the past 20 years, with a tendency to accumulate toward the lower part of the river. In Shanghai, the nitrogen concentration is twice as high as at the Three Gorges Dam, the survey's starting point. On the other hand, the phosphate concentration remained constant at a relatively low level.