Don’t Rely on Plankton to Save the Planet
Encouraging plankton growth in the ocean has been touted by some as a promising way to remove carbon dioxide from the atmosphere. _____(1)_____
Adding iron to patches of ocean can make plankton bloom temporarily. The microscopic organisms suck up dissolved carbon dioxide from the water, which in turn is replaced by carbon dioxide from the air. _____(2)_____
Jorge Sarmiento from Princeton and his colleagues developed a complex computer model to analyse how factors such as ocean chemistry and water circulation would affect the process if 160,000 square kilometers of ocean were seeded with iron for a month. _____(3)_____
In their scenario, which covers an area 10 times as big as the largest experiment of this kind ever proposed, fertilizing the ocean removes 1 million tones of carbon from the atmosphere—just 0.2 per cent of the carbon dioxide humankind spews out each month.
Rough estimates in the past have predicted similarly disappointing results. _____(4)_____says Sallie Chisholm, an environmental engineer from the Massachusetts Institute of Technology. “But the take-home message is the same. _____(5)_____”
A Its opponents argue, however, that it will stop global warming.
B Its opponents fear that it will damage the marine ecosystem, and now a computer model shows that the trick would also be remarkably inefficient.
C As plankton die an settle on the ocean floor, their carbon is supposedly locked up in the seabed.
D They found that 100 years later only between 2 and 11 per cent of the extra carbon that was originally taken up by plankton had actually been removed from the atmosphere.
E “These are newer and better models,”
F Ocean fertilization is not the answer to global warming.
Dung to Death
Fields across Europe are contaminated with dangerous levels of the antibiotics given to farm animals. The drugs, which are in manure sprayed onto fields as fertilizers, could be getting into our food and water, helping to create a new generation of antibiotic-resistant “superbugs”.
The warning comes from a researcher in Switzerland who looked at levels of the drugs in farm slurry. _____(1)__________
Some 20,000 tons of antibiotics are used in the European Union and the US each year. More than half are give to farm-animals to prevent disease and promote growth. _____(2)_____
Most researchers assumed that humans become infected with the resistant strains by eating contaminated meat. But far more of the drugs end up in manure than in meat products, says Stephen Mueller of the Swiss Federal Institute for Environmental Science and Technology in Dubendorf.__________(3)_____
With millions of tons of animals manure spread onto fields of crops such as wheat and barley each year, this pathway seems an equally likely route for spreading resistance, he said. The drugs contaminate the crops, which are then eaten. _____(4)_____
Mueller is particularly concerned about a group of antibiotics called sulphonamides. _____(5)_____ His analysis found that Swiss farm manure contains a high percentage of This concentration is high enough to trigger the development of resistance among bacteria. But vets are not treating the issue seriously.
There is growing concern at the extent to which drugs, including antibiotics, are polluting the environment. Many drugs given to humans are also excreted unchanged and are not broken down by conventional sewage treatment.
A They do not easily degrade or dissolve in water.
B And manure contains especially high levels of bugs that are resistant to antibiotics, he says.
C Animal antibiotics is still an area to which insufficient attention has been paid.
D But recent research has found a direct link between the increased use of these farmyard drugs and the appearance of antibiotic-resistant bugs that infect people.
E His findings are particularly shocking because Switzerland is one of few countries to have banned antibiotics as growth promoters in animal feed.
F They could also be leaching into tap water pumped from rocks beneath fertilized fields.
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