Environ. Sci. Technol. 1997, 31, 806-812
Occurrence of PCDD/F in Dated Lake Sediments of the Black Forest, Southwestern Germany INGRID JU ¨ T T N E R , * ,†,‡ BERNHARD HENKELMANN,† KARL-WERNER SCHRAMM,† C H R I S T I A N E . W . S T E I N B E R G , †,§ RAIMUND WINKLER,| AND ANTONIUS KETTRUP† Institut fu ¨r O ¨ kologische Chemie Neuherberg and Institut fu ¨ r Strahlenschutz Neuherberg, GSF-Forschungszentrum fu ¨ r Umwelt und Gesundheit GmbH, D-85764 Oberschleissheim, Germany
Despite concerns about the toxicity of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F), there are still few data on their past trends in Middle Europe. Here, we use paleolimnology to assess the occurrence of PCDD/F in sediments of four remote Black Forest lakes where atmospheric deposition has been the only possible input. Considerable quantities of PCDD/F occurred in the sediments of one lake before the production of chlorophenols in the 1920s, emphasizing that they are not only recent contaminants. On the basis of homologue profiles typical for soots, we suggest that fossil fuels burned since industrialization were a major source at this time. PCDD/F loadings in sediments accelerated in the 1930s at one site and in the 1960s at three others. Changes in homologue profiles were lake-specific but generally implicated sources in waste incineration, combustion of fossil fuels, and metal processing. Peak TEQ of 205.2 and 228.7 ng/kg occurred respectively in sediments from 1964 to 1985 at Wildsee and from 1982 to 1992 at Herrenwieser See. Despite the small geographical area represented by the lakes, their historical trends in PCDD/F burden differed due probably to variations in local and regional sources. This indicates that more extensive surveys than those often available are required to ensure representative data on regional patterns of contamination.
Introduction PCDD/F originate from the production and application of chlorophenols and their derivatives and from pulp bleaching, thermolytic processes, and combustion (1-3). Sources can vary within geographical regions (2, 4-7) and time periods (8-11). Atmospheric transport via dust particles leads to accumulation in sink areas such as lake sediments in remote places away from direct inputs (12, 13); in these cases, trends will reflect the overall atmospheric burden. In the absence of past monitoring data, paleolimnological approaches are * Corresponding author fax: 0044-1222-874305; e-mail: Juttner@ Cardiff.ac.uk. † Institut fu ¨r O ¨ kologische Chemie Neuherberg. ‡ Present address: Catchment Research Group, PABIO, University of Wales, Cardiff, P.O. Box 915, Cardiff CF1 3TL, U.K. § Present address: Institut fu ¨ r Gewa¨ssero¨kologie und Binnenfischerei, Mu ¨ ggelseedamm 310, 12587 Berlin, Germany. | Institut fu ¨ r Strahlenschutz Neuherberg.
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FIGURE 1. Location of the study area: 5, Herrenwieser See; 6, Schurmsee; 7, Wildsee; 8, Huzenbacher See; S, Strasbourg; K, Kehl; O, Offenburg; F, Freudenstadt; BB, Baden-Baden; R, Rastatt; H, Hornisgrinde Mountain; 1, Rhine; 2, Murg; 3, Rench; 4, Kinzig. central to determining such trends, but studies in Middle Europe are especially scarce (8, 14). Here, as elsewhere in the world, trends from adjacent lakes are seldom assessed on the assumption that individual patterns are representative (7). This study is the first to replicate the assessment of trends of PCDD/F over ca. 3-400 years in lakes sufficiently close for the same deposition history to be expected.
S0013-936X(96)00503-2 CCC: $14.00
1997 American Chemical Society
b
a
c
d
FIGURE 2. PCDD/F homologue profiles in lake sediments from Herrenwieser See (a), Schurmsee (b), Wildsee (c), and Huzenbacher See (d), Northern Black Forest, southwestern Germany (ng/kg).
Study Area The Herrenwieser See (surface area 1.8 ha, catchment 0.18 km2), Schurmsee (1.4 ha, 0.64 km2), Wildsee (2.4 ha, 0.24 km2), and Huzenbacher See (0.9 ha, 0.09 km2) are spring-fed forest
lakes within a radius of 20 km in the northern Black Forest at 747-910 m (Figure 1). The lake sediments are anaerobic, with average sedimentation rates from 4.0 to 18.6 mg cm-2 a-1; chironomid tubes were absent, and no other evidence
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TABLE 1. PCDD/F and I-TEQ in Lake Sediments from the Northern Black Forest, Southwestern Germany Herrenwieser See
PCDD/F (ng kg-1)
flux (pg cm-2 a-1)
I-TEQ
Schurmsee
PCDD/F (ng kg-1)
flux (pg cm-2 a-1)
I-TEQ
1982-1992 1960-1982 1927-1960 1886-1927 18th Century 17th Century
18388 7079 1154 430 270 238
81.3 31.3 20.3 1.9 1.1 1.0
229 110 17 4 0.5 0.4
1987-1992 1979-1987 1965-1979 1946-1965 19th Century 18th Century
3010 1564 423 537 268 317
49.8 31.8 11.7 10.4 5.0 5.9
31 23 7 9 0.4 0.1
Wildsee
PCDD/F (ng kg-1)
flux (pg cm-2 a-1)
I-TEQ
Huzenbacher See
PCDD/F (ng kg-1)
flux (pg cm-2 a-1)
I-TEQ
time period
1985-1992 1964-1985 1930-1964 1892-1930 ca. 1850-1892 early 19th Century
13559 16490 8029 1371 483 489
64.7 88.9 49.4 12.0 2.2 2.2
157 205 130 25 9 8
1983-1992 1961-1983 1903-1934 1882-1903 19th Century 18th Century
8996 19743 153 455 136 758
120.9 167.6 1.6 5.6 1.7 9.4
69 90 0.7 2 0.2 1
1 2 3 4 5 6
for bioturbation has been found. Prevailing winds are from south-southwestern to western directions transporting air masses from the densely populated and industrialized Rhine Valley. Atmospheric deposition is the only source of pollution since the lakes receive neither direct sewage inputs nor are they close to any agricultural land, human settlements, or roads. All are heavily acidified due to industrial emissions of acidifying substances (15-17).
Materials and Methods Sediment cores of 6 cm diameter were taken in April (Herrenwieser See, Schurmsee, Huzenbacher See) and September (Wildsee) 1992 at the deepest part of each lake (7-13 m) using a gravity corer (Core-Stecher System Niederreiter, Limnological Station Mondsee, Austria). The cores were immediately sectioned into 2-cm slices, and the samples were stored at 4 °C in sealed glass containers. Sediments were dated using 210Pb and 137Cs as well as other dateable irregularities in the sediment profiles (16). The average dry matter content of the sediment slices used for the analysis was 6.3% at Herrenwieser See, 8.9% at Schurmsee, 11.3% at Wildsee, and 9.0% at Huzenbacher See. Details of PCDD/F analysis and quality assurance data are given elsewhere (16, 18). Samples were freeze-dried, and 1.4-10 g of sediment was Soxhlet-extracted for 24 h with toluene, spiked with at least one 13C12-labeled internal standard per homologue group. The cleanup procedure included sequential liquid chromatography on alumina, silica, and Florisil. Quantification and detection were performed on a high-resolution gas chromatograph (60 m TR × 2330 polar capillary column, Restek, and 60 m DB-5 column, J&W, for HpCDF, OCDF, and OCDD) and by mass spectrometry in EI mode by tracing the M+, (M + 2)+, or the most intensive ions of the isotope cluster (Finnigan MAT 95, R ) 10 000, and Finnigan MAT 8230, R ) 5000). Toxicity equivalents (I-TEQ) were calculated based on toxicity equivalent factors (TEF) for individual congeners (NATO/CCMS), where 2,3,7,8-tetrachlorinated dibenzo-pdioxin (2,3,7,8-TCDD) is the most toxic substance with a TEF value of 1. Principal component analysis (PCA, SPSS for Windows 6.0.1) was performed to compare PCDD/F homologue pattern from the Black Forest lake sediments with patterns found in various environmental samples and samples from potential sources. The data were normalized by dividing the homologue concentrations by the ∑PCDD/F to give percentage values (3).
Results and Discussion General Trends. PCDD/F were detected in sediments from the 17th to the 19th Century onwards with toxic equivalents
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FIGURE 3. PCDD/F input pattern from Wildsee, Northern Black Forest, southwestern Germany (pg cm-2 a-1). Input changes were determined by subtracting congener-specific flux rates in each time period from corresponding values in the preceding time period. (I-TEQ) below 1 ng/kg. Sediments at this time were dominated by octachlordibenzodioxin (OCDD) in Herrenwieser See (Figure 2a), comparable with results from 8000-year-old marine sediments (9) and 19th Century sediments from Green Lake (New York) (19). In contrast, in Huzenbacher See, octachlordibenzofuran (OCDF) dominated in the 18th Century, but OCDD dominated in the 19th Century (Figure 2d). Tetrachlordibenzofurans (TCDF) dominated the old sediments from Schurmsee (Figure 2b). Furans predominated
FIGURE 4. (a) Principal component analysis (PCA) on homologue patterns from various environmental samples (8, 19, 25, 27, 31; Kraus personal communication). 1, Huzenbacher See 1903-1934; Schurmsee 1987-1992; Wildsee 1985-1992. 2, Lake Constance 1955-1956, 1956-1963, 1963-1970, 1970-1976; Wildsee 1964-1985; Herrenwieser See 1982-1992; domestic waste incineration. 3, River Rhine sediment Gambsheim 1985; atmospheric deposition Baden-Wu1 ttemberg 1992-1993. 4, Huzenbacher See 1961-1983. 5, Schurmsee 18th Century, 19th Century; Herrenwieser See 1927-1960; Lake Constance 1944-1954. 6, Wildsee early 19th Century, Wildsee ca. 1850-1892; Schurmsee 1946-1965, 1965-1979; Herrenwieser See 1960-1982; chimney soot from oil central heating. 7, chimney soot from oil central heating; a wood oven; a coal oven; an oil oven and a wood-coal oven. 8, chimney soot from a coal oven. 9, chimney soot from oil central heating; wood central heating; an oil oven and a wood oven. 10, chimney soot from a coal oven and wood central heating. 11, Wildsee 1930-1964; TCB from Dynamit Nobel. 12, Schurmsee 1979-1987; Lake Constance 1954-1955. 13, Lake Constance 1976-1981. 14, Huzenbacher See 18th Century, 19th Century, 1882-1903. 15, Herrenwieser See 1886-1927; Huzenbacher See 1983-1992; 16, Herrenwieser See 17th Century; River Danube sediment from Ulm 1979; River Kinzig sediment 1985; River Neckar sediment from Lauffen 1979; River Rhine sediments from Rust 1985, Strassbourg 1985, and Iffezheim 1985; compost from Baden Wu1 rttemberg 1990s. 17, soil from a metal recycling company at Crailsheim. 18, soil from a metal recycling company at Rastatt. (b) Herrenwieser See and Schurmsee and (c) Wildsee and Huzenbacher See show chronological changes in the homologue pattern of lake sediments along the principal components. Each point is labeled with the time period given in Table 1. at Wildsee in sediments deposited in the 19th and the early 20th Century (Figure 2c). Homologue patterns in these early sediments could conceivably reflect the natural formation of PCDD/F (20). However, varying degradation between congeners originating from combustion or differential loss from the sediments due to bioturbation, resuspension, diffusion, and microbialmediated dechlorination are also possible (11, 21-23). Assessments of congener-specific degradation rates in natural sediments are scarce: working from a core from the Baltic Proper, Kjeller and Rappe (11) suggested that half-lives for PCDD were well over 100 years; half-lives for furans decreased with increasing chlorination from 80 years in TCDFs to 30 years in OCDF. Among all these explanations of our data, we believe that atmospheric deposition from anthropogenic sources is the most likely. First, differences between lakes and time periods in degradation processes would have to be large to be responsible for the observed data. Second, the smelting of ores and the production of charcoal and pottash for the numerous local glass industries were local sources of emissions in the 17th-19th Centuries (10, 24, 25). Iron ores were exploited from the 17th Century and smelted in Bu ¨hlertal 10 km west-northwest of Herrenwieser See between 1683 and 1802. A glass factory operated between 1724 and 1778 just
2.5 km west-southwest of this lake. In the 18th and 19th Centuries, glass factories also operated close to Schurmsee and Huzenbacher See. Pottash was produced for the glass industry within a distance of only 5 km from Herrenwieser See, Schurmsee, and Wildsee. Although we cannot exclude degradation of PCDD/F in the lake sediments, these emission sources have almost certainly affected the lakes (16) and are the most likely explanation for the different homologue pattern in the early sediments. In Herrenwieser See and Wildsee, PCDD/F loadings and I-TEQ increased substantially after the onset of commercial production and incineration of chlorophenols in the late 1920s (Table 1, Figure 3). However, the I-TEQ value was already 10 times higher than background at Herrenwieser See in sediments deposited between the 1890s and the 1920s, and a I-TEQ of 25 ng/kg had been reached by this period at Wildsee, preceding commercial chlorophenol production; other sources must thus have been important. Trends in Homologue Pattern. Different PCDD/F sources were also reflected by changing homologue profiles within the lakes and by different homologue patterns in different lakes (Figure 2a-d). When homologue profiles from several environmental samples and emission sources were compared using PCA, the first two principal components represented
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TABLE 2. Total and Individual PCDD/F in Sediment Samples from the Northern Black Forest, Southwestern Germany (pg g-1) Herrenwieser See
sum of TCDD sum of PnCDD sum of HxCDD sum of HpCDD OCDD sum of PCDD 2,3,7,8-TCDD 1,2,3,7,8-PnCDD 1,2,3,4,7,8-HxCDD 1,2,3,6,7,8-HxCDD 1,2,3,7,8,9-HxCDD 1,2,3,4,6,7,8-HpCDD sum of TCDF sum of PnCDF sum of HxCDF sum of HpCDF OCDF sum of PCDF 2,3,7,8-TCDF 1,2,3,7,8/1,2,3,4,8-PnCDF 2,3,4,7,8-PnCDF 1,2,3,4,7,8/1,2,3,4,7,9-HxCDF 1,2,3,6,7,8-HxCDF 1,2,3,7,8,9-HxCDF 2,3,4,6,7,8-HxCDF 1,2,3,4,6,7,8-HpCDF 1,2,3,4,7,8,9-HpCDF
Schurmsee
19821992
19601982
19271960
18861927
18th Century
17th Century
19871992
19791987
19651979
19461965
19th Century
18th Century
102 354 1157 4708 5199 11519 3.9 29 55 69 106 2528 1053 1783 1533 1669 831 6869 119 180 154 167 167
