A survey of the spatial, altitudinal, and temporal distribution of chlorinated paraffins in the Alpine region

Chlorinated paraffins (CPs) have been produced since 1930 and are still used in a wide variety of consumer products and industrial processes. In the last decades, CPs represented one of the largest group of chlorinated hydrocarbons produced in North America and Europe. In spite of the knowledge of their long-range transport, bioaccumulation, potential of carcinogen for rats and mice, and toxicity for aquatic organisms, information on the levels and fate of CPs in the environment is insufficient. This results from analytical difficulties associated with the quantification of CPs because of the complex composition of commercial formulations. Production and use of short chain CPs (SCCPs, C10-13) have been regulated in the European Community and in Switzerland due to their significant bioaccumulation and toxic potential. Furthermore, SCCPs are now under evaluation for inclusion into the Stockholm Convention on Persistent Organic Pollutants (POPs).
The aim of this work was to investigate several aspects of the environmental fate of CPs in Switzerland and in the Alps. For this purpose, available analytical methodologies for sediments and biota were adapted and improved for soil/humus, compost and conifer needles. Furthermore, a unified analytical approach suitable for the determination of CPs in various matrices is presented, which has the benefit of a standardized clean-up after a matrix specific extraction. The extraction and clean-up is kept as simple and efficient as possible in order to make this methodology applicable in routine laboratories environment. The very selective clean-up allowed to eliminate interferences and enables the use of low resolution mass spectrometry (LRMS).
Gas chromatography combined with electron ionization tandem mass spectrometry (EI-MS/MS) was used for the determination of total CPs (sum of short, medium (MCCPs, C14-17), and long chain CPs (LCCPs C>17)). SCCP and MCCP levels as well as congener group patterns (n-alkane chain length, chlorine content) could be evaluated by electron capture negative ionization low resolution mass spectrometry (ECNI-LRMS).
The alpine region was the target area, since the Alps are surrounded by regions with significant industrial activities and a high population density. Due to barrier effects, high precipitation rates and low ambient temperatures, the Alps are supposed to act as a geographical and meteorological trap for atmospheric pollutants including semivolatile organic compounds.
The first study presents altitude profiles and the spatial distribution of CP levels in humus layers and spruce needles collected within the Monitoring Network in the Alpine Region for Persistent and other Organic Pollutants (MONARPOP) project. CPs were present in all samples; their concentrations varied between 7 and 199 n/g dry weight (dw) and from 26 to 450 n/g dw in humus and needle samples, respectively. Elevated concentrations were observed for altitude profiles in humus samples taken between 700 and 900 m as well as between 1300 and 1500 m. A clear vertical tendency could not be ascertained for the individual altitude profiles. No correlation could be observed in the needle samples due to higher variations of the data. Data for environmental airborne CPs on spruce needles are presented for the first time providing evidence that spruce needles are a suitable passive sampling system for the monitoring of atmospheric CPs.
CP levels were determined in ten soil samples from reference sites of the Swiss national soil monitoring network (NABO). The aim of this study was to achieve the load of CPs in Switzerland. For this purpose, EI-MS/MS was used for the determination of total CP amounts. Total CP concentrations were between 34 and 151 n/g dw. These concentrations are comparable to soil concentrations from the MONARPOP project. ECNI-LRMS measurements revealed SCCP concentrations of 2-51 n/g dw and MCCP concentrations of 15-85 n/g dw.
Furthermore, three compost samples from Switzerland were analyzed. EI-MS/MS analysis revealed concentrations of 182-614 n/g dw for total CPs and ECNI-LRMS measurements of 57-140 n/g dw for SCCPs and 29-245 n/g dw for MCCPs.
A dated sediment core from Lake Thun covering the last 120 years was analyzed to get an overview of the historical trend of the CP deposition. Studies of dated sediment cores are an excellent way to investigate concentration trends over decades. Total CP concentrations showed a steep increase in the 1980s and a more or less stable level of 50 n/g dw since then. The concentration-time profile was in good agreement with the available information on global production data. Levels of higher chlorinated SCCPs have risen in recent years. In addition, the degree of chlorination of SCCPs has strongly increased during the past 40 years, which may indicate its use as an additive for polymers, paints and coatings. CPs were also compared with polychlorinated biphenyls (PCBs) analyzed in these dated sediment slices. The peak level of CPs exceeded that of PCBs by about a factor of three. Comparison of both temporal trends showed an increase of CPs when PCB levels declined.
Generally, the total CP levels were considerably higher than the indicator PCB levels analyzed in all studies.