Peatlands: a major sink of naturally formed organic chlorine.

It is a little known fact that many chlorinated organic compounds occur naturally and that some are also indispensable to life on earth. Here, we show that chlorination of organic compounds during humification processes in peat is widespread in nature. Globally this process has led to the accumulation of approximately 280-1000 million tons of organically bound chlorine in peatlands during the postglacial period.