Formation of Chlorinated Hydrocarbons in Weathering Plant Material

When we think of chlorine, we often relate it to the salt used in food preparation, chloride in the oceans, chlorine gas from swimming pools, and gaseous chlorofluorocarbons that have close links to the depletion of stratospheric ozone. We rarely think of thousands of chlorinated hydrocarbons that exist in the natural systems, several of which are highly toxic to humans (1). The C-Cl bond, common to all organo-Cl compounds, is strong and gives high stability to organo-Cl compounds. For this reason, several organo-Cl compounds have been synthesized and used extensively for years in agricultural and industrial applications. For the same reason, these molecules tend to stay in the environment for a longer time, and threaten to contaminate aquatic and soil systems (2). There are also reported occurrences of bioaccumulation of anthropogenic chlorinated compounds in areas remote from human settlements (3,4), and such widespread distribution of organo-Cl compounds is believed to be due to the high stability of man-made organohalogens and their long-range transport in the environment. The behavior and the ultimate fate of organo-Cl compounds in the environment are not well understood, and need a critical evaluation using the in-situ molecular techniques.