Halogen Retention, Organohalogens, and the Role of Organic Matter Decomposition on Halogen Enrichment in Two Chilean Peat Bogs

• Published in: Environmental science & technology Vol. 38; no. 7; pp. 1984 - 1991
• Main Authors: Biester, H, Keppler, F, Putschew, A, Martinez-Cortizas, A, Petri, M
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.04.2004
• Subjects: Applied sciences; Atmospheric pollution; Biodegradation, Environmental; Bromine - chemistry; Chile; Chlorine; Chlorine - chemistry; Decomposition; Dispersed sources and other; Ecosystem; Environmental Monitoring; Exact sciences and technology; Iodine; Iodine - chemistry; Mosses; Organic Chemicals - metabolism; Pollution; Pollution sources. Measurement results; Retention; Soil; Water Supply; South America; Chile; America; Biodegradation; Natural origin pollution; Heathland and moor; Organic matter; Atmospheric fallout; Pollutant formation; Troposphere; Wet deposition; Retention; Pollutant emission; Peat; Peat bog; Biogenic factor; Chlorine Organic compounds; Air pollution; Air ground interface; Ombrotrophic peat bog
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es0348492

Natural formation of organohalogen compounds can be shown to occur in all natural environments. Peat bogs, which are built up exclusively of organic matter and cover approximately 3% of the total continental world area, are potentially significant reservoirs for organohalogen formation. Up to now, fluxes and retention rates of halogens and organohalogen formation in peat bogs were mostly unquantified. In our study, we investigated the retention of atmospheric derived halogens and the natural formation of organohalogens by differential halogen analysis in two peat bogs in southernmost Chile. Atmospheric wet deposition rates of chlorine, bromine, and iodine range between 600 and 36000, 6 and 160, and 1 and 3 mg m-2 yr-1, respectively. Mean annual net accumulation rates of these halogens in peat are calculated to be 12−72 mg of Cl m-2, 1.7−12 mg of Br m-2, and 0.4−1.2 mg of I m-2. Retention rates are similarly high for iodine (36−46%) and bromine (7.5−50%), and substantially lower for chlorine (0.2−2%). To evaluate influences of peat decomposition processes on halogen enrichment, halogen concentrations were compared to carbon/nitrogen ratios (C/N). Our results indicate that up to 95% of chlorine, 91% of bromine, and 81% of iodine in peat exist in an organically bound form. The results also indicate that the concentrations of halogens, especially of bromine and iodine, in peat are largely determined by peat decomposition processes and that halogens are not conservative in bogs.