Workers deal with water lettuce on a refuse-removal boat in Chongqing on Sunday. [Photo by Ran Wen/For China Daily] In recent days, a large quantity of invasive water lettuce has appeared on the surface of the Yangtze River in Chongqing, clogging waterways and threatening the safety of boats. After heavy rains on the upper reaches of the river last week, the plants washed into Chongqing on Saturday at about noon. Large amounts soon gathered in the middle of the river and along the banks. On Tuesday, the city's maritime department issued a warning and asked boats to avoid the floating plants. The species, introduced from overseas, is among the world's most productive freshwater plants. It is found in nearly all tropical and subtropical freshwater areas. As it often grows into dense mats that clog channels, China has listed it as one of its 100 most dangerous invasive species. In addition, water lettuce will also block the exchange of air, reducing oxygen in the water and killing fish. Large mats can also block light and alter underwater plant communities. At present, the main way to control water lettuce is to physically remove it and transport it to onshore disposal areas. This is the second time this year that water lettuce has been found in downtown Chongqing, said Di Hongwei, of Chongqing Water Environment Co, which cleans the city's waterways. The company scoops out garbage and storm debris to make waterways more scenic and easier to navigate. Flood season is the busiest time of year for river cleaners. Last month, the company removed more than 1,000 metric tons of water lettuce from the river. The work took a week. We didn't find water lettuce last year, Di said. But there was a large quantity of it in 2015. In some backwater bays, the plants were so dense that a man could stand on them. To speed up the cleaning, the company has sent three large refuse removal boats and hired another four to remove the plants around the clock. It expects to take a week to finish the work. Chongqing, a megacity of 30 million people, is located on the upper reaches of the Yangtze, the world's third-longest river at 6,300 kilometers. Since the Three Gorges Dam was built, the river's water level rises in winter and drops in summer, opposite the natural cycle. Garbage on the river's surface creates unpleasant scenery and difficult navigation for ships. Trash can even affect the production of electricity at the dam. In recent years, Chongqing has removed more than 5 million tons of garbage from the river. silicone braceletsrubber wristbands ukadjustable wristbandsprintable wristbandswrist band com coupon codepersonalized silicone bracelets
SHENYANG -- Chinese scientists have developed an artificial sponge material that can separate oil and water to be used for treating water contaminated by industrial sewage.A paper on the research undertaken by the Institute of Metal Research under the Chinese Academy of Sciences was published on the latest issue of the international journal Advanced Materials Interfaces.The porous material made with nano-crystalline cellulose and graphene composite has a high absorption capacity. It is 97 percent effective in water and oil separation, according to Liu Dongyan, a researcher with the institute based in Shenyang, capital of North China's Liaoning Province.Liu said that industrial sewage contains various oils and organic components that are ecologically hazardous once mixed with water. The new material provides a low-cost industrial sewage treatment solution.She explained that the base material of the polyurethane sponge is cost-effective. Only the small amount of graphene in the coating is still expensive. However, with the increasing production of graphene in China, the price would gradually come down.
