办事指南

UN fumes, China fumigates

点击量:   时间:2019-03-07 11:15:06

By Fred Pearce EMBARRASSINGLY, for a nation hosting a major international conference, China has been cited as the main culprit in the explosive growth in the use of the fumigant methyl bromide. This pesticide is threatening to undermine the achievements of the Montreal Protocol, which has cut emissions of ozone-destroying chemicals by 85 per cent since 1989. Methyl bromide, which kills the nematodes, bugs and weeds that threaten strawberries, tomatoes and flowers, is now the third most important cause of ozone destruction, after CFCs and halons. Use of the pesticide in developing countries, often on crops destined for export to Europe and North America, has doubled over the six-year period between 1991 and 1997. Israel is currently the world’s largest manufacturer of the chemical, but looks likely to shortly pass the baton to China. Use of methyl bromide in China tripled between 1995 and 1997, says Sebastian Oberthuer, analyst of ozone trends for the German research agency GTZ in Eschborn. China has expanded a large methyl bromide manufacturing plant at Lianyungang, north of Shanghai. Oberthuer’s colleague Peter Stoermer says that the plant’s capacity is now 3000 tonnes per year, approaching 10 per cent of global production. China has also so far failed to ratify the 1992 Copenhagen Amendment to the Montreal Protocol, which added methyl bromide to the list of chemicals to be phased out. Equally ominously, China’s report to the conference, outlining programmes to cut emissions of ozone-destroying chemicals, made no mention of methyl bromide at all. In a recent showdown with Chinese officials, the UN Environment Programme warned that any further assistance in converting industry to ozone-friendly chemicals will depend on China’s approval of the Copenhagen Amendment, according to UNEP official Rajendra Shenda. But simple alternatives to the pesticide do exist. Volkmar Hasse of GTZ has shown that a simple piece of plastic sheeting could replace the nerve toxin in killing pests. Farmers have used plastic sheeting and manure to reduce the amounts of the chemical that are released into the atmosphere (New Scientist, 7 November 1998, p 11), but results from studies in Jordan and elsewhere over two years show that they can abandon the pesticide entirely. Instead, farmers can kill pests by covering their soil in plastic, irrigating underneath and waiting for the Sun to boil the water and sterilise the soil. And in Morocco, Hasse has demonstrated a system of protecting tomatoes by grafting onto the plants a root stock that poisons nematodes. Both systems, he says, are cheaper than methyl bromide. More on these topics: