China’s recent economic boom has come at the cost of polluted landscapes and newly endangered species, and now a new study explains how another species has been left teetering on the brink of extinction. The endangered Chinese sturgeon live in the East China and Yellow seas and return to China’s Yangtze River to spawn. Construction of dams on the river is thought to have contributed to a decline in the species, and an artificial propagation effort has not resulted in recovery of the fish [AP]. But the new study shows that a chemical called triphenyltin (TPT), which is commonly used in paint, may be the true culprit behind the sturgeon’s decline.
The tin-containing organic compound TPT is extensively used in paints to prevent the fouling of ship hulls and fishing nets. It is also used in fungicide to treat crops in China. A derivative of TPT is also used to eliminate snails in paddy fields [Reuters]. In the study, published in the Proceedings of the National Academy of Sciences, researchers found that river water polluted with the chemical is producing sturgeon with misshapen skeletons and deformed eyes.
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China’s plan to build dams along the Mekong River poses the greatest threat to the river’s future, according to a United Nations report released yesterday. China is constructing a series of eight dams on the upper half of the Mekong as it passes through high gorges of Yunnan Province, including the recently completed Xiowan Dam, which — at 958 feet (292 meters) high — is the world’s tallest. Its storage capacity is equal to all the Southeast Asia reservoirs combined [AP], according to the report.
The Mekong, which is known as the Lancang in China, is an important source of water, food, and jobs for residents in the river basin, and runs through China, Myanmar, Laos, Thailand, Cambodia and Vietnam. It provides a habitat for rare species of bird and marine life. If the dams move ahead, said the report, the consequences will include “changes in river flow volume and timing, water quality deterioration and loss of biodiversity” [AP]. But Chinese Foreign Ministry spokesman Ma Zhaoxu defended the proposed plans, saying China would give equal attention to hydropower development on transnational rivers and ecological protection [Xinhua].
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If global warming trends continue unabated, the Colorado River won’t have enough water to supply the 27 million people who depend on it, according to a new study. Less runoff — the snow and rain that fortify the 1,400-mile river — caused by human-induced climate change could mean that by 2050 the Colorado won’t be able to provide all of its allocated water 60 percent to 90 percent of the time, according to two climate researchers [AP].
The Colorado River flows through seven states in the American Southwest and continues into Mexico. It supplies water to households, businesses, factories, and farms, and is also home to several endangered species of fish. The study’s lead researcher, Tim Barnett, says that the findings indicate that tough decisions will have to be made about who will get less water. Agricultural operations use about 80 percent of the water taken out of the Colorado, Barnett said. He knows the arguments, though: Shorting farms could drive up food prices. Curbing development in cities and suburbs will make developers unhappy. Whatever the case, he said, some decisions need to be made soon. “The actions that need to be taken aren’t going to be fun,” Barnett said. “It’s not going to be life as usual” [AP].
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One-third of China‘s Yellow River is no longer fit for any use, and only one-sixth is safe to drink, according to a bulletin released over the weekend by the Chinese government. It reported the results of a 2007 study that surveyed water quality along the 5,464-kilometer-long river, which has become increasingly polluted from booming riverside industries and raw human sewage. Li Xiaoqiang of the Yellow River Conservancy Committee, which ran the study, called for “urgent action” to save the river, and added forlornly: “I wish that a harmony could be achieved between development, utilisation and protection of the river someday” [Telegraph].
The 2007 study monitored the river’s mainstream and its 35 tributaries, with the combined length totaling 13,492.7 km, and found 4,557.6 km, or 33.8 percent of the waterways monitored, to have polluted water classified as type-five negative [XinHua]. The United Nations Environmental Program considers level five water to be unfit for drinking, aquaculture (such as fish farming and oyster farming), agriculture, and industrial use. Only 16.1 percent of the river water was rated level one or two, considered safe for drinking and household use. Of the 4.29 tons of pollution discharged into the river, industry and manufacturing contributed 70 percent and human sewage made up most of the rest, the bulletin reported. Specific pollutants were not reported. Wen Bo of the environmental group Pacific Environment said “It’s not surprising…They are just treating the river as a dumping site. It’s basically a sewage channel for the provinces that share the river” [AP].
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In a new study that’s already generating controversy, researchers tracked more than 1,000 young Pacific salmon on their first journey to the sea, and found that those battling dams on the Columbia River fared no worse than the young fish with an easier path to the sea on Canada’s free-flowing Fraser River. The findings seem to contradict many previous studies about dams: Conservationists have blamed these obstacles for a large share of the shrinking salmon populations in the Pacific Northwest, and engineers have spent billions trying to make the dams less damaging to salmon [Science News].
The study used implanted transmitters to follow the juvenile salmon, called smolts, on their trips downriver, and found that only about 25 percent of smolts in both the Columbia and the Fraser survived the voyage and made it to the ocean. But environmentalists and several salmon biologists pounced on the study, suggesting that industry funding might have biased the results. These critics question the value of comparing the two rivers and say that the study doesn’t even address what many think is the dams’ biggest effect: stressed smolts dying after they reach the ocean [Nature News].
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