Temporal Trends of C8-C36 Chlorinated Paraffins in Swedish Coastal Sediment Cores over the Past 80 Years.

Temporal trends of chlorinated paraffins (CPs) were analyzed in three sediment cores collected near different potential CP sources along the Swedish Baltic Sea coast. C8-C36 CPs were found in sediment dating back to the 1930s. The maximum CP concentrations found in proximity to a metropolitan sewage treatment plant, a wood-related industrial area, and a steel factory were 48, 160, and 1400 ng/g d.w., respectively, in sediment sections dated from the early 1990s or the 2000s. The temporal trends agree with statistics on CP importation in Sweden or local industrial activities. MCCPs (C14-C17 CPs) and LCCPs (C≥18 CPs) predominated in most sediments with average percentage compositions of 47 ± 20% and 37 ± 20%, respectively. Concentrations of SCCPs in the three cores showed a decreasing trend in recent years. The temporal trends of MCCPs indicated that these are currently the predominant CPs in use. This study showed for the first time that LCCPs from C18 to C36, as well as C8-C17 CPs, are persistent in sediments over the last 50-80 years, indicating that CPs are persistent chemicals regardless of alkane-chain lengths.