Quantification of Natural Organic Chlorine Compounds in Multiple Environmental Compartments by Complementary Methods

Work in recent years has shown that the element chlorine has a complex biogeochemical cycle. Naturally occurring organic chlorine compounds exist in soil in concentrations similar to other important elements, like phosphorus. The chlorine cycle and terrestrial mass balance are poorly understood relative to other major elements, and this work seeks to characterize the chlorine cycle in a Connecticut urban-forested watershed. This study presents preliminary results on the quantification of the abundance of chloride and organic chlorine compounds from multiple environmental compartments, such as precipitation, dry deposition, surface water runoff, soil, biomass, and leaf litter. Total organic halide (TOX) is the traditional method used for analyzing organic chlorine, but this method does not reveal the speciation of organic chlorine. This study applies gas chromatography with electron capture detection (GC-ECD) to quantify the abundance of methyl chloride, chloroform, and other natural occurring compounds. Standardization of GC-ECD for the analysis of natural occurring organic chlorine compounds represents an important step in quantifying the flux of the various organic and inorganic chlorine species in a watershed. A fundamental understanding of the chlorine biogeochemical cycle is necessary for future work aimed at how human activity, such as the use of deicing road salt, alters the mass balance.