Chlorine in nature

  • 30/07/1995

The US Environmental Protection Agency is likely to cut down or ban the production of chlorine and compounds containing it.

However, many scientists believe that even were manufacture of chlorine-containing chemicals to be prohibited, their creation would not cease. Nature produces many of them, more than 1500, with more being discovered. Some are highly toxic, while others are benign such as those present in edible seaweed. The simplest natural organochlorine is methyl chloride (CH3CI). It is produced by marine algae, kelp, wood-rotting fungi, and some terrestrial vegetation. In total, the annual global emission rate of CH3CI is 5 million tonnes.

Annual manmade emissions total 26,000 tonnes.

Furthermore, the smoke of burning wood contains more than 100 organochlorine compounds. These include scores of polychlonnated dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Among them is the highly toxic dioxin (2, 3, 7, 8 tetrachlordibenzo-p-dioxin). The PCDDs can withstand temperatures of nearly 100 degree Calsius in the presence of excess oxygen.

two research groups have concluded that forest and bush fires are major sources of PCDDs. It has been estimated that annually as much as 60 kilogrammes of PCDDs are produced on an average in Canadian forest fires. In addition to Canadian emissions. forest fires elsewhere and domestic woodburning in the developed and especially in the less developed countries generate a much larger amount. This in turn is supplemented by.slash-and-burn agriculture. According to Science magazine, manmade production of dioxin has decreased during the last two decades and is smaller than that created by combustion of wood.

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