Polycyclic aromatic hydrocarbons in Recent lake sediments—I. Compounds having anthropogenic origins

Polycyclic aromatic hydrocarbons in Recent lake

0016.7037 80~0301-0403102.00/0

sediments-I. Compounds having anthropogenic origins

STUART G. WAKEHAM.* CHRISTIAN SCHAFFNER and WALTER GXER

Swiss Federal Institute for Water Resources and Water Pollution Control (EAWAG), CH-8600 Diibendorf. Switzerland

(Received 22 Jntluar)~ 1979: accepted i~t reoised,form 22 October 1979)

Abstract-Polycyclic aromatic hydrocarbons (PAHj in sediment cores from Lake Lucerne, Lake Ziirich. and Greifensee. Switzerland. and Lake Washington. northwest U.S.A.. have been Isolated, identified and quantified by glass capillary gas chromatography and gas chromatography/mass spectrometry. Surface sediment layers are greatly enriched in PAH-up to 40 times--compared to deeper layers. In addition, concentration increases in upper sediments generally correspond to increasing industrialization and urbanization in the catchment basins of the lakes. Few PAH could be detected in pre-industrial revolution sediments. indicating that background levels for most PAH in aquatic sediments are extremely low.

These results are consistent with an anthropogenic source for most of the aromatic hydrocarbons present in the modern sediments. A comparison of PAH distributions in the sediments and m possible source materials shows that urban runoff of street dust may be the most important PAH input to these lacustrine sediments. There is evidence that a significant contribution to the PAH content of street dust comes from material associated with asphalt. -

INTRODUCTION

THE WIDESPREAD occurrence of complex assemblages of polycyclic aromatic hydrocarbons (PAH) and their alkylated homologs in soils and Recent aquatic sediments has been well dQcumented (GIGER and BLUMER, 1974; BLUMER et al., 1977; BLUMER and YOUNGBLOOD, 1975; HITES and BIEMANN, 1975; YOUNGBLOOD and BLUMER, 1975; GIGER and SCHAFFNER, 1977, 1978; LAFLAMME and HITES, 1978; and others) since chrysene (KERN, 1947) and benzopyrenes (BLUMER, 1961) were first detected in soils. In most cases, these aromatic hydrocarbons have anthropogenic origins. Increased levels of fossil fuel (primarily coal) combustion over the past 751OOyr are probably responsible for the elevated PAH concentrations in the surface sediment layers compared to deeper layers in several lakes (GRIMMER and BBHNKE. 1975; MUELLER et al., 1977). In a marine sediment. HIT= er nl. (1977) report a similar correlation between the vertical PAH content of a coastal marine sediment core and aromatic hydrocarbon production estimated as a function of fuel consumed. PAH are known products of pyrolysis and combustion (LEE er al., 1976. 1977; GRIMMER et al., 1977), and are widely dispersed by the atmosphere when adsorbed onto soot and airborne particulate matter (LUNDE and BJORSFTH. 1977). Thus LAFLAMME and Htr~s (1978) and WINDSOR and HITES (1979) attri- bute the finding of low levels of PAH in sediments remote from combustion sources, at least in part, to long-range atmospheric transport. In addition. PAH sorbed onto waterborne particulate matter (e.g. street dust washed from roads) can be transported in rivers,

* Present address: Department of Chemistry. Woods Hole Oceanographic Institution, Woods Hole, MA 02543. U.S.A.

lakes, and oceans. Spillage of petroleum and its refined products, both of which contain extremely complex mixtures of aromatic hydrocarbons (YOUNGBLOOD and BLUMER, 1975; WAKEHAM, 1977) may add to the anthropogenic contribution of PAH to Recent sediments. In view of the known carcinogenic properties of several PAH (ARCO~ and ARGUS, 1968; NAS, 1972) continued contamination of and dispersal throughout the environment by this class of compounds may pose an increasing health hazard.

The presence of natural sources for PAH in Recent sediments is controversial. Earlier experiments sug- gested that some organisms were capable of biosyn- thesizing these hydrocarbons (GRAEF and DIEHL, 1966; KNORR and SCHENK. 1968; BORNEFF et al., 1968; MALLET and TISSIER. 1969; HANCOCK et al., 1970). However, more recent results indicate biological ac- cumulation rather than actual biosynthesis (HASE and HIRES, 1976a). Nevertheless, some PAH apparently are generated by post-depositional transformations of biogenic precursors over relatively short time periods: perylene is a well-documented example (AIZENSHTAT, 1973; WAKEHAM, 1977; LAFLAMME and HITES, 1978). Ancient sediments and petroleums contain complex mixtures of aromatic hydrocarbons formed by dia- and catagenesis of organic matter (TI~~oT and WELTE. 1978). Thus weathering of ancient sediments and natural petroleum seeps could contribute PAH to Recent sediments in some areas. Natural forest and prairie fires have also been proposed as important PAH sources (BLUMER and YOUNGBLOOD, 1975;

YOUNGBLOOD and BLUMER, 1975); again. however, there are arguments to the contrary (HASE and HIT& 3976b; HIRES et al., 1977). In any event, distinguishing between the many diverse PAH sources is difficult. Aspects of analytical approaches for distinguishing

403

404 STUART G. WAKEHAM. CHRISTIAN SCHAFFNER and WALTER GIGER

between various PAH sources have been discussed

elsewhere by YOUNGBLMID and BLUMER (1975) and LAFLAMME and HITES (1978).

To better assess the origins (anthropogenic and

natural) and the modes of dispersal (atmospheric, water-borne. etc.) of the PAH which are accumulated in Recent aquatic sediments, we have undertaken a detailed investigation of the distributions of aromatic

hydrocarbons in four lakes. three in Switzerland and one in the north-western United States. Our emphasis was to develop a historical record and thereby follow changes in PAH inputs to the Lake sediments and, where possible, to distinguish among the several likely sources. A series of short cores (up to about 60 cm in

length and covering c 180 yrs’ history) were analyzed to provide detailed depth profiles at different loca-

tions and depositional environments within a single lake (Greifensee, Switzerland). Longer cores (ranging in length from 1 to 6 m) from four widely separated

lakes (Greifensee. Lake Ziirich and Lake Lucerne. Switzerland, and Lake Washington, U.S.A.) were examined to cover a much longer time scale (- 300 to _ 15.000 yr) and more varied depositional environments. The results of this investigation are presented in two parts: Part I (this paper) deals with PAH derived from anthropogenic activities; Part II (WAKE- HAM et al., 1980) describes a number of aromatic hydrocarbons which appear to be generated by short-

term diagenetic processes within the Recent lake sediments.

MATERIAL AND METHODS

Esrraction und isolariorl of the P.4 H

The analytical methodology used in this study has been described in detail by GIGER and SCHAFFNER (1978). Dry samples (2-5Og sediment) were Soxhlet extracted with methylene chloride. The extracts were concentrated in a rotary evaporator at room temperature. Elemental sulfur was removed by percolation through a column of activated copper. This eluate was evaporated, dissolved in a mini- mum of benzene-methanol (I :l) and subjected to gel per- meation chromatography (Sephadex LH-20). The same benzene-methanol solvent mixture was used to elute two 50ml fractions: the first highly pigmented eluate contain- mg aiiphatic and oletinic hydrocarbons. esters, and pig- ments. and the second containing the PAH. The aromatic hydrocarbons were then further purified by chromatography on fully activated silica gel (Merck Kieselgel 40). with a relatively clean PAH mixture being eluted by methylene chloride after washing with pentane. Estimates of weights of the PAH isolated were obtained by weighing aliquots of each fraction on a Cahn 4100 electrobalance.

Gus chromuroyraphy (GC)

Gas chromatographlc Identification and quantification of individual components in the PAH isolates were carried out on a Carlo Erba (Model 2101 AC) apparatus equipped with a Grob injector (GROB and GROR, 1972) and a flame ionization detector. Glass capillary columns (20 m x 0.3 mm i.d.) coated with SE-52 according to the barium carbonate procedure of Grob (GROB and GROB, 1976; GROEI et al.. 1977) were routinely used to separate the individual PAH. Samples (l-2 pl of methylene chloride solutions) were injected without stream splitting onto the

column at ambient temperature. After elutlon of the solvent. the oven temperature was programmed from 70 to 25o’C at Z’C,min. Hydrogen carrier flow was maintained with back pressures of 0.7-l.Oatm in order that coronene would elute at about 250°C from columns with film thick- ness of about 0.15 pm.

Quantitation was performed by comparing peak areas. obtained by electronic integration (Spectra-Physics ‘Mini- grator’), of the PAH with that of an internal standard. I-chlorotetradecane. which was added to the PAH-containing solutions immediately before GC analysis. Repro- ducibility of the extraction-isolation-GC procedure. based on replicate analyses of PAH reference mixtures and well- homogenized sediment samples containing several levels of PAH. was better than +25”; in most cases. Reported PAH concentrations have been corrected for analytical re- coveries and procedural blank content. An average detection limit of l-2 rig/g sediment over the range from fluorene to coronene is estimated.

Gus cllrornaroyraplly,mass spectromrtr~ (GC !\ilS)

A Finnigan GC’MS system (Model 1015D) interfaced to an on-line computer (Model 6ooO) was used for mass spectrometric identifications and mass chromatography. The SE-52 capillary column was directly coupled to the mass spectrometer with a platinum capillary. GC conditions were similar to those described above except that helium was the carrier gas and consequently back pressures were approximately doubled.

LOW coifayr muss sprctromefr,v (LKMS)

All PAH concentrates were qualitatively scanned by the probe distillation-low voltage (I2 eV) mass spectral technique described by YOUNGBL~~D and BLUMER (1975). This technique gives the mass spectrum of the total PAH sample (or any fraction thereof over a selected probe temperature range) and indicates the presence or absence of higher molecular weight PAH that are not amenable to conventional GC analysis. It also provides information on relative abundances of alkylated members of homologous series of PAH. Although under certain conditions LVMS can provide quantitative information on homolog distributions. we did not use the technique in this mode.

Total organic carbon content of sediment samples were determined with an F & M model I85 CHN analyzer. Prior to analysis. sediments were treated with 0. I N HCI to remove carbonates and dried at 80°C.

SAMPLES

Lake sedimenrs

Sediment cores were collected from four lakes for PAH analyses. The general character of the lakes and cores is outlined in Table I.

Grr@lsrr. Five cores were collected from the highly eutrophic Greifensee. a small perialpine lake (surface area 8.6 km’. maximum depth 32 m) in a densely populated region about II km southeast of Ziirich. Switzerland. Cores A. B. C. and D, each of approximately 60 cm length. were obtained in April. 1976 with a gravity corer and were stored frozen at - 22’C prior to sectioning and freezedry- ing. Sample locations A and B were at the deltas of two small rivers which discharge mto Greifensee (Mijnchal- torfer Aa and Aabach, respectively), station C was close to the deepest point in the lake. and station D was near the northeast lake shore but remote from Huvial inuuts.

The fifth and much longer core E (640 cm) was obtained from H. P. WEBER (Swiss Federal Institute of Technology. Ziirich) and had been collected from the lake’s central

Polycyclic aromatic hydrocarbons in Recent lake sediments 405

Table I. General characteristics of the lake sediment cores -___--___-- ___ -~ --__--__

lake water Core Sedimentation Sediment Type Organic Lake Condition Land Condirion Depth Secrion Rate Carbon

(m) (cm) (mm/v) RanRe (X) At Time of Sedimentation -- --

Greifensee A 8 o-2 9 9 13 O-4‘ t HD i

Lacustrine Marl 4.1-5.2 2.9-7.4 i Eutrophic t Urbanized

c 30 o-59 3-81 Sapropel/?fud 2.2-7.4 D 8 0-4; 3-e’ i 2.7-7.7 \ Oligo- t0 1 Increaslngl” E 15 O-60 3-8’ Sapropel/Mud 2.7-5.6

\ Eutrophic \ Urbanized

ho-350 0.3-0.5: Lacustrine Chalk 3.6-4.7 Oliao- t0 Farested

Lucerne

Mesbtrophic 350-640 I-22 Posrplacial Mud 1.3-1.4 Oligotrophic Tundra

110 O-20 23 7 1 Sapropellnud

2.0-4.5 Lightly Urbanized 20-104 2.1-2.2 i

Hesocrophic Rural

zuricil 136 O-40 5’ 2.1-6.6 Heaviiv Urbanlred *Cl-104 i SaproPelfWd

2.0-2.2 t Mesotrophic Small ?OW”S

57 O-20 35

I

4.9-5.6 ?le*o- t0 Heavzl? Urbanized Eutrophic

20-35 4.55 SaprspellMud 3.9 Mesotrophic Small Towns/ Lumbering

35-385 0.6 596 ! 4.4-7.1 Oligotrophic Forested

ND = Could not be determined. ‘Based on ““Pb measurements (G~GGELER et al.. 1976, TSCHOPP, 1978) and on counting annual varves (EMERSON and

WIDMER. 1978). 2Estimates, partially based on 14C measurements (WEAER. 1979). %TAUB (1979). 4N~~~~~ (I 927). ‘Based on “‘Pb measurements (SCHELL. 1974), and EDMONDSO~’ and ALLISON (1970) ‘GOULD er <II. (unpublished manuscript); MEHRINGER et al. (1977).

basin (depth I5 m) In August. 1976 using a modified Kul- lenherg piston corer. This core has been stored approximately six month at 4’C before sampling for hydrocarbon analyses.

Data on analyses of aliphatic and olefinic hydrocarbons in these Greifensee cores and further information about the sampling locations and the condition of Greifensee itself are described elsewhere (GIGER cr a[.. 1980; WEBER, 1979).

Lake Lucerne. Lake Lucerne is located in central Swit- zerland and is X-shaped. with arms ranging in length from 3 to about 35 km. and up to 4 km in width. The maximum water depth is Z I4 m. A l-m long gravity core was collected in October. 1976 at the intersection of the four arms (Kreuztrichter) in 1 IO m water.

Lake Ziirich. Situated in north-central Switzerland, Lake Ziirich is 40 km long and 24 km wide. A gravity core (1 m) was sampled in October, 1976 off the town of Thalwil at the deepest point in the lake (136 m).

Luke Washington. Lake Washington is in western Wash- ington State. U.S.A. The lake is 25 km long and 3-4 km wide. and has a maximum depth of 62 m. Sediment samples were from a gravity core (MOcm) and a piston core (4&380cm) (depths in the two cores were correlated and aligned by comparing aliphatic hydrocarbon content) collected bj J. HWGES and R. CARPENTER (University of Washington) in June. 1977. The sampling site corresponds to Madrona Park station of WAKEHAM and CARPENTER ( 1976). who have described in detail the aliphatic hydrocarbon distributions in Lake Washington sediments.

All four lakes are located in relatively densely populated areas. with Lakes Ziirich and Washington having the high- est drainage basin populations (approximately 200.000 and 700.000 Inhabitants. respectively). Therefore, urban storm water runoff from the adjacent shores enters all four lakes. The three Swiss lakes also receive varying amounts of treated sew’age effluents: Lake Washington, however. has received no sewage effluents since about 1968.

PAH source muterids

Analyses of PAH distributions were also carried out on a number of materials which could be important sources of

PAH present in lake sediments. Street dust samples were swept from asphalt and concrete roads in the Diibendotf area which have varying levels of automobile traffic. Weathered asphalt was collected by breaking a piece from the surface of an old but little used asphalt-surface road. Several samples of fresh asphalt were obtained from the Swiss Federal Institute for Materials and Testing (EMPA). Diibendorf. Samples of automobile exhaust were also obtained from EMPA; these were collected by passing the exhaust from a standardized dynamometer test (about 4 m3/sample) through a paraffin-impregnated filter. Petro- leums and refined fuel products were obtained from local sources. Aromatic hydrocarbon fractions of all of the above samples were isolated by the procedure used for the sediments.

RESULTS AND DISCUSSION

Greifensee short cores A-D

Analytical results for the four short Greifensee cores are summarized in Fig. I, which shows depth

profiles for total organic carbon. total aromatic hy-

drocarbon content (gravimetric), and three selected individual PAH (phenanthrene. fluoranthene. and 3,4-benzopyrene). The capillary gas chromatogram of

PAH isolated from O-3 cm in Greifensee (Fig. ZA) is typical of the composition found throughout these four cores.

For the two delta stations (cores A and B), concentrations of organic carbon and PAH fluctuate and show no obvious trend with depth. This is consistent with *“Pb data (TSCHOPP, 1978) which indicate that these sediments have been intensely mixed. probably during periods of high discharge from the two small rivers. Despite this variability, two interesting features are evident: (I) In core B, the maximum levels of


CORG I%1 TOTAL AROMATICS IN/q,

0, 2 3 4 5 6 7 8 0 loo 200 MO 4M 500

---o

44.49’ ‘i, t 49-w. ‘F .i 54-59. d .i

CONCENTPATION (q/91

0 Kxx zoo0 34x 4cCoo m0 zoo0 3Cco 4Ow 5m 0 too0 xx)0 ’

PHENANTHRENE FLUORANTHENE .4-EENZOPYRENE

GREIFENSEE CORES A-D

Fig. I. Analytical results for the Greinfesee short cores (A, B. C. and D). For cores A and B. sediment ages are unknown; for cores C and D. 60cm corresponds to about 1800 (see Table I).

PAH are in the deepest core section. The reason for this finding is not known, but clearly there must have been a higher local PAH input sometime in this area in the past. (2) Aromatic hydrocarbon content in core B was usually higher than in core A. This observation points out the importance of urban hydrocarbon

sources compared to rural inputs. The Aabach (river) which enters Greifensee near station B flows through an urbanized area before discharging into the lake and contains effluents from a sewage treatment plant located close to the lake shore. In contrast, the drain-

age basin of the smaller Monchaltofer Aa, which dis- charges near station A, is primarily a rural environ-

ment. Cores C (central basin) and D (nearshore but dis-

tant from river mouths) contain generally lower PAH concentrations than were present in the delta sediments. Levels in D are slightly lower than in C. The concentration difference between the core A-B pair and the C-D pair may be due to preferential deposit- ion of PAH-containing particles in the delta areas compared to transport and subsequent sedimentation in regions more distant from the in-flowing rivers. It should also be noted that in both C and D, PAH levels generally decrease with increasing depth, showing that recent PAH inputs are greater than those in

the past. Both cores, however, provide information only as far back in time as about 1800.

Similar patterns of individual PAH were observed in gas chromatograms for all depths in cores A-D (Fig. 2A). Although absolute concentrations vary con-

siderably (for example, Fig. I), relative abundances of individual constituents were quite constant from sample to sample. Unsubstituted ring systems ranging from acenaphthene (two aromatic rings) to coronene (seven fused rings) were the primary components

(Table 2). Most possible isomeric ring types (linear, clustered, and angular) were represented. However, angular molecular configurations (e.g. phenanthrene

and chrysene) were present in greater concentrations than the corresponding linearly annelated isomers, which were either less abundant (anthracene, _ IO’?; of phenanthrene concentration) or were not detected (tetracene). This observation suggests that linear structures are produced less readily at the source and/or are less stable in the environment. Unidenti- fied ring systems of still higher molecular weight, and which are not amenable to GC analysis, were detected by probe distillation-low voltage mass spectrometry. Thus the sedimentary PAH have a compositional

complexity even greater than is revealed by high reso- lution GC.

Polycyclic aromatic hydrocarbons in Recent take sediments

GRElFENSEE

Fig. 2. Class capillary pas chromatograms of PAW isolated from Greifensee core E surface O-3 cm (A} and 203-208 cm (8) sediment. Numbers refer to identified compounds listed in Table 2. CC-conditions: ?Om x 0.3 mm i.d. Pyrex capillary with barium carbonate interlayer and coated with SE-ST. i,Oatm hydrogen as carrier gas. Bane ioRi~atjo~ detector. column at ambient temperature’ during injection and elution of the solvent, then programmed from 10 to 25o’C at a rate al Xlmin. The large peak (e) clurinp between the rnetb~~chr~se~e series (15) and the benzofluoranthe~e group (161 is a phthalate

contaminant picked up at random during sample processing.

An extremely complex mixture of alkylated deriva- tives af most unsubstitoted PAH species was also present. These alkyl homologs account for many more components than the unsubstituted members. Com- pounds containing more than six carbon atoms in alkyd side chains were detected by the low vottage mass spectral technique. Within a given homologous series. each additional alkyl carbon atom results in a nearly twofold concentration decrease. Cycio-alkylated aromatic hydrocarbons, such as 4,5-methylene- phenanthrene, were also relatively abundant.

Investigations to date dealing with PAH distributions in aquatic sediments have concentrated either on surface sediments only (GIGEH and BLUMER, 1974; Yo~~~a~~o and BLUMER, 1975; GIGER and SCHAFFNER. 1977; LAFLAMME, and HITES. 1978) or on short sediment cores covering about the last 100 yr or less @SRIMMFR and B~HNKE. 1975; MUELLER et uL,

1977; HITES ef al.. 1977). To alleviate the obvious lack of information for Recent sediments deposited before the industrial revolution could inAuence them. analyses were carried out on four cores of greater length which would coyer greater time periods and more diverse environmental conditions in the four di~erent lakes. For example, the 6-m Greifensee core (E) extends back in time some 15,Wyr BP and covers three distinct and w~Il*de~ned periods jrab)e 1). The Lake Washington core has a maximum age of about 3000yr BP.

Con~ntrations of total aromatic hydro~rbons (gravimetric) and the sum of concentrations for the major individual PAW as determined by gas chromatography are illustrated in Fig. 3 (note that the concentration scale is logarithmic). As is often the case with analyses of very complex mixtures, the quantitation of individuai components by gas chromatography accounts for only a small portion of the total weighable aromatic fraction. concentrations of individual PAM as shown in Fig. 4 for selected sec.

108 STCART G. WAKEHAM. CHRISTIAN SCCIAFFVER and WALTER GIGER

Table 2. Polycyclic aromatic hydrocarbons Identified in lake sediments

Peak Number Compound

1 Acenaphthene 2 Fluorene 3 Phenanthrene 4 Anthracene 5 Methylphenanthrenesa 6 4,5+iethylenephenanthrene 7 Dimethyl/ethylphenanthrenes a Fluoranthene 9 Pyrene 10 1,2-Benzofluorene 11 2,3/3,4_Benzofluorenes 12 1,2_Benzofluoranthene 13 1,2-Benzanthracene 14 Chrysene/triphenylene 15 Methylchrysenes 16 Benzofluoranthenes 17 1,2-Benzopyrene 18 3,4-Benzopyrene 19 Perylene 20 Indeno (1,2,3-cd)pyrene 21 1.2,3,4/1,2,5,6-Dibenzanthracenes 22 1,12-Benzoperylene 23 Anthanthrene 24 Coronene S Internal Standard

A In order of elution: 3-Methylphenanthrene. 2-Methylphenan-

threne, 9-Methylphenanthrene, I-Methylphenanthrene.

LAKE ZORICH

LAKE LUCERNE

LAKE WASHINGTON

SECTION IN CORE (em)

Fig. 3. Depth profiles of PAH in the four long lake sediment cores showing concentrations of total aromatic fraction (by gravimetry) and the sum of major Individual PAH (by gas chromatography). Concentration scale is logarithmic. Ages of sediment sectlons are approximate, based on data m Table I. For the 403-408 cm and 603-608 cm sections of the Greifensee core, concentrations of Individual PAH

as determined by GC totaled < 0.1 {lg, g.


63-68cm

203-208cm

n

Fig. 4. Concentrations of individual PAH in four sections of Greifensee core E. Concentration scale is logarithmic. Compound numbers refer to those listed in Table 2. Note that methylchrysenes (IS) are omitted. Approximate ages for the sediment depth intervals are 1975, 1930. 1900. and

3000 BP respectively.

tions of the 6m Greifensee core E are typical for sediments of similar ages for all four cores.

In agreement with initial data from Greifensee

cores C and D (Fig. I ). surface sediment layers of long cores from each of the four lakes are enriched in PAH [both total fraction (Fig. 3) and individual compo-

nents (Figs 3 and 4)] compared to deeper and older sediments in the respective lakes. Before about 1850.

sediments accumulating in each lake apparently incorporated somewhat uniform levels of PAH. and the levels were. within minor variations. constant

from lake to lake. In terms of individual PAH. few compounds were detected in pre-industrial revolution

sediments (samples deeper than 60 cm in Fig. 4 and in the chromatogram in Fig. 2B). Exceptions are a homologous series of phenanthrenes and perylene, all of which are apparently products of short-term post- depositional reactions. as will be discussed in more detail in Part II.

Since Cu 18.50. inputs of PAH to the environment as recorded and preserved in lake sediments have greatly increased. The result is very much elevated levels of a wide range of aromatic hydrocarbons in the more recent sediment layers. The overall composition of PAH in these younger sediments resem-

bles those discussed above for Greifensee cores A-D.

Significantly. the concentration increases generally

parallel industrial growth worldwide, although the

maximum concentration reached in the sediments

varies by lake. Enrichment of PAH in Lake Lucerne. for example, is about five times the earlier value. Lake

Ziirich surface sediments. however. contain some fort! times more PAH than were found in pre-1850 layers. This means not only that lake sediments pro- vlde a sink for anthropogenically-derived PAH and

can thus preserve the history of inputs, but also that different aquatic systems receive these inputs at vari-

able levels. In the case of Lakes Lucerne and Ziirich. it is apparent that Lake Ziirich sediments receive

greater amounts of PAH from more intense sources than the sediments of Lake Lucerne. This is reason-

able smce the Lake Ziirich catchment basin is more

heavily industrialized and populated than the Lake

Lucerne region.

PA H Sourws

The overall PAH distribution found in surface sediment layers of the three Swiss lakes and Lake Wash- ington is not unique to these water bodies. Such a

pattern is common in recently deposited sediments and has been described in marine (GIGEK and BLUMER. 1974; YOUNGBL~D and BLUMER. 1975;

LAFLAMME and HITES. 1978; HIRES rt al., 1977) and freshwater (GRIMMER and BBHNKE. 1975: MCILLER rr

al.. 1977; GICER and SCHAFFNER, 1977, 1978) sediments and in soils (YOUNGBLOOD and BLUMER, 1975;

LAFLAMME and HIT-ES. 1978) from a variety of locations and environments. The ubiquitous nature of this PAH mixture suggests both a common origin and widespread sources and/or dispersal.

BLUMER and YOUNGBLOOD (1975) and YOL:NGBLOOD and BLUMER (1975) have proposed natural combus-

tion processes (natural forest and prairie fires) as the primary source of PAH in Recent sediments. Our evidence argues against such B proposal. If natural fires were to provide a significant PAH input to the en-

vironment. and if the lake sediments reflect PAH pro-

duction in the environment. then one might expect to find a relatively constant level of PAH throughout

recent history (assuming a constant level of natural fires and a high degree of persistence of PAH within

the sediment column). Obviously this is not the case in the sediments investigated. since there is a dramatic increase in PAH concentrations in the upper sedimentary layers. In fact. there are apparentI) few aromatic hydrocarbons at concentrations above a few ng’g (with the exception of compounds formed by early diagenetic processes: see Part II) present in lake sediments older than about 150yr. These results. how-

ever. do not rule out completely a minor input from natural fires. Such an input could either be below our analytical detection limits or would be swamped by a much greater input from other present-day sources.

Enrichment of polycyclic aromatic hydrocarbons in the most recent11 deposited lacustrine (and marine)


sediments can readily be attributed to anthropogenic combustion and pyrolysis sources. PAH are known to

be formed during fossil fuel combustion (GRIMMER et ul.. 1977: LEE et al., 1977) and sorbed onto atmospheric particulate matter (LAO et al.. 1973; LEE rc ~11.. 1976, 1977; LUNDE and BJORSETH, 1977). The atmosphere is an efficient dispersal mechanism. A comparison by HASE and HITES (1976b) of PAH distribution in an estuarine sediment and in the local atmosphere

indicates that a primary source of PAH to the aquatic environment is anthropogenic combustion-produced compounds emitted to the atmosphere. Thus, HITES et al. (1978) correlate the observed depth profile for PAH in a coastal marine sediment core with increasing fossil fuel combustion and LAFLAMME and HITES

(1978), and WINDSOR and HITES (1979) show the possible importance of long-range transport of PAH from combustion source to remote sediments. Indeed. the PAH distributions in the lake surface sediments are qualitatively very similar to PAH on airborne particulates (LAO et al.. 1973; LEE er al., 1976. 1977:

LUNDE and BJORSETH, 1977; GIG~R and SCHAFFNER. 1978), although some natural processes may have modified the PAH homolog pattern during and after

sedimentation (HASE and HITES. 1976b: LAFLAMME and HITES, 1978).

Thus atmospheric contamination by pyrolysisicom-

bustion-produced PAH must be considered as a

source of at least some portion of the PAH found in surface sediments of the three Swiss lakes and of Lake Washington. Emission to the atmosphere of greater

amounts of combustion-derived PAH in recent years could account for elevated concentrations in the most recently deposited sediments. However, while deposit- ion of atmo:phericaily-transported PAH may consti-

tute the predominant source of these compounds to soils and sediments remote from direct anthropogenic influence, we believe that. at least in the case of the four lakes we studied. a greater contribution may be

via PAH present in material washed off of streets and roads in the lakes’ drainage basins. Certainly street runoff will contain some atmospherically-deposited material, but we maintain that a significant PAH load comes from road-wear material. mainly PAH associ-

ated with asphalt particles. Our evidence and reasoning are as follows. Street

dust is operationally defined here as that material

which may be mechanically swept up from a road. and as such may contain PAH from several sources:

aeolian fallout. asphalt particles. tire particles. auto-

mobile exhaust condensate and particulates. and lubricating oils and greases. The PAH content of street dust (Fig. 5A) collected from a local asphalt road (the overwhelming majority of roads in the lakes’ drainage basins are asphalt-surfaced) has a high correlation (molecular weight range. predominance of

i

Fig. 5. Capillary gas chromtograms of PAH isolated from a street dust (A) and weathered asphalt (B). Numbers refer to identified compounds in Table 2. GC conditions as for Fig. 2. In A, the phthalate (01 is

present (see Fig. 2). while in B it is absent.


unsubstituted PAH, alkyl-substituted homolog pattern) with PAH present in surface sediments. Dust from a cement road had a similar qualitative distribution but a lower PAH loading. Combustion-produced and airborne particulate PAH also have similar PAH distributions (LAO et al., 1973; LEE et al.. 1976, 1977; LUNDE and BJORSETH, 1977; GIGER and SCHAFFNER. 1978) except that the lower molecular weight region (phenanthrenes. fluoranthene, pyrene) is often de- pleted somewhat reiative to higher molecular weight (benzfluoranthenes, etc.) compounds. This may, however. partly be a sampling artifact. Microscopic exam- ination of street dust samples shows many tar-like particles which appear to be asphalt; similar particles are visible in some lake sediments having high PAH content. Many of these particles in street dust range in size up to approximately 5OOpm. compared to automobile exhaust particles which are generally smaller than about 50pm (BOYER and LAITINEN, 1975). Asphalt taken from an old road has a PAH distribution (Fig. SB) similar to that of street dust and

, !’

the surface lake sediments. In contrast, fresh asphalt contains a more complex mixture of PAH in which few compounds actually predominate. It is likely that the PAH distribution of the weathered asphalt and street dusts reflects, at least in part, combustion-derived material associated with the particulate matter.

The significance of asphalt-road abrasion as a means of contaminating air and surface waters with PAH, particularly 3,4-benzopyrene, has also been shown by WAIBEL (1976) who compared PAH content of roadside dust and storm runoff water from asphalt- and cement-surfaced roads. Despite compositional similarities for dusts from both road types (our analyses), PAH loadings in dust and runoff associated with asphalt roads were invariably several times higher than loadings from cement surfaces. Assuming similar contributions to the street dusts in Waibel’s study from atmospheric dustfall. tire wear particles, and automobile exhaust (both road types had similar levels of vehicular traffic), the marked difference in the quantity of PAH being released into the

A) TIRE

B) AUTO EXHAUST

Fig. 6. Capillary gas chromatograms of PAH isolated from tire particles (A) and automobile engine exhaust (B). Numbers refer to identified compounds in Table 2. In B: a = alkylbenzenes. b = naphthalene. c = 2-methyinaphthalene, d = I-methylnaphthalene. e = C,-naphthalenes. f = C,-naphthalenes.

GC conditions as for Fig. 1.

412 STUART G. WAKEHAM. CHRISTIAN SCHAFFNER and WALTER GIC~ER

environment from these two types of road surfaces

must be attributed to asphalt particles. The probable mode of delivery of street dust and the associated

PAH to lakes is via storm water runoff during rain

storms, followed by transport as river and stream particulate matter. This would also account for the relatively high concentrations of PAH in riverborne particulates (GIGER and SCHAFFNER, 1978) and in the Greifensee delta sediments.

Our analyses also help us to dismiss automobile tire-wear particles and automobile engine exhaust as major sources of the PAH present in the street dusts

and in the lake sedments. Tire wear-particulates may indeed be found in street dusts, especially dusts from

cement-surfaced roads. However, as shown in Fig. 6A, the PAH distribution of a tire sample is very different from the PAH assemblages in the street dusts and

sediments. In addition to a much narrower boiling range for the tire PAH compared to the sediments, most major components in the tire aromatic hydrocarbons are sulfur- and nitrogen-containing compounds. This should not be too surprising considering the abundance of heteroaromatic molecules in carbon black (LEE and HITES, 1976). an important raw mater-

ial used in tire manufacturing. These heteroaromatic compounds are only trace constittients of the lake

sediment PAH fractions. Automobile exhaust, on the other hand, contains

primarily low boiling aromatic hydrocarbons, the most abundant being alkylbenzenes, and naphthalene

and alkylated naphthalenes (Fig. 6B). Several unsubstituted PAH. including phenanthrene, fluoranthene, and pyrene are present as minor constituents, but other higher molecular weight PAH are scarce enough to be detected only by CC/MS or LVMS. Clearly the qualitative PAH distribution in the automobile exhaust will not account for the much wider range of aromatic hydrocarbons in surface sediments

unless the PAH mixture in the exhaust undergoes extensive modification during transport to and ac- cumulation in the lake sediments.

SUMMARY AND CONCLUSIONS

(1) A rich assemblage of PAH is present in Recent sediments of our lakes. The major components are unsubstituted species, although many alkylated de- rivatives are also found at lower concentrations. Simi- lar qualitative patterns of PAH were observed in the surface sediment layers from each of the four lakes, regardless of the lake’s location and the level of anthropogenic activity in its catchment basin.

(2) Surface sediments are enriched in PAH com-

pared to deeper layers, in which few PAH could be detected. Those few aromatic hydrocarbons which are abundant in the deep layers are apparently derived from early diagenetic processes (see Part II, WAKE’-

HAM et n[., 1980). The elevated concentrations of PAH in the most recently-deposited sediments generally correlate with industrial and urban growth in the

region surrounding each lake, thereby indicating an anthropogenic origin for these sedimentary aromatic

hydrocarbons. (3) A comparison of PAH content in the lake sedi-

ments and several source materials suggests that urban runoff containing street dust particles is poss- ibly the major present-day source for the PAH in the lakes we investigated. This street dust material is washed from roads during heavy rain storms. transported by rivers and streams. and eventually accumulated in the lake sediments. Furthermore, our results

suggest that asphalt particles in the street dusts may be an extremely important contributor to the PAH

content of the lake sediments. Although it is difficult to evaluate the relative contribution of asphalt particles compared to fallout of atmospheric particulate

matter, we believe that the input of asphalt-associated aromatic hydrocarbons to lake sediments m densely populated areas must be significant.

Acknowlrdyemrnrs-We are most grateful to Professor K. GROE and G. GROB for assistance with the glass capillary gas chromatographic analysis of the PAH and for supply- ing the SE-52 columns. The 6-m Greifensee core was made available by H. P. WEBER. Geological Institute. Swiss Federal Institute of Technology, Ziirich (ETHZ). the Lake Washington sediments were obtained from Dr J. HEDGES. Dr R. CARPENTER, R. C. CLARK. JR and co-workers. Uni- versity of Washington. Seattle. and the automobile exhaust sampies were provided by the Swiss Federal Institute for Materials Testing IEMPA). Diibendorf. We thank Dr H. A. LEIDNER for the organic carbon determinations.

The continued interest and useful discussions throughout this investigation of Professor W. S~U~M are most appreciated. We also thank J. W. FARRINGSD~. C. LEE and S. M. HENRICHS for their reviews of the manuscript.

This work was supported in part by the SWISS Depart- ment of Commerce (Commission of the European Commu- nities Project COST 64 b).

REFERENCES

A~ZENSHTAT A. (1973) Perylene and its geochemlcal sigmti- cance. Geochim. Cosmochirn. Acta 37. 559-567.

ARCO~ J. C. and ARGUS M. F. (1968) Molecular geometry and carcinogenic activity of aromattc compounds. New perspectives. Adc. Camv Res. 11, 305-471.

BLUMER M. (1961) Benzpyrenes m soil. Science 134. 474-475.

BLUMER M. and YDUNGRLOOD W. W. (1975) Polycyclic aromatic hydrocarbons in soils and recent sediments. Science 188, 53-55.

BLUMER M.. BLUMER W. and REICH T. (1977) Polycyclic aromatic hydrocarbons in soils of a mountain valley: correlation with highway traffic and cancer incidence. Environ. Sci. T&no/. I 1. 1082- 1084.

BORNEFF J.. SELENKA F.. KUNTE H. and MAXIMOS A. (1968) Experimental studies on the formation of polycyclic aromatic hydrocarbons in plants. Environ. Rrs. 2, 22-29.

BOYER K. W. and LAITINEN H. A. (1975) Automobile exhaust particulates. .&iron. Sci. E&no/. 9, 457-469.

EDMONDSON W. T. and ALLISON D. E. (1970) Recordmg densitometry of X-radiographs for the study of cryptic laminations in the sediment of Lake Washington. Lim- nol. Oceanoyr. 14. 3 17-326.

EMERSON S. and WIDMER G. (1978) Early diagenesis in anaerobic lake sediments-II. Thermodynamic and kin- etic factors controlling the formation of iron phosphate. Geochim. Cosmochun. Acta 42. I307- 13 16.


GAGGLER H.. VON G~JNTE~: H. R. and NYFFELER U. (1976) Determmation of *“Pb in lake sediments and in air samples by direct gamma-ra? measurement. Earflt Plu-

net. sci. Lert. 33, 119-121. GIGER W. and BLUMER M. (1974) Polycyclic aromatic hv-

drocarbons in the environment: isolation and characteii- zation by chromatography. visible. ultraviolet. and mass spectrometry. Anal. C’hem. 46. 1663- I67 I.

GIGER W. and SCHAFFNER C. (1977) Aliphatic. olefinic. and aromatic hydrocarbons in recent sediments of a hIghi> eutrophic lake. In: Adcatwc in Organic Geochcmisrr~~

(eds R. Campos and J. Goni), pp. 375-390. ENADIMSA. GIGER W. and SCHAFFNER C. ( 1978) Determination of poly-

cyclic aromatic hydrocarbons in the environment by glass capillary gas chromatography. Alla/. C/zc,m SO. 243-249.

GIGER W., SCHAFFNER C. and WAKEHAM S. G. (1980) Aliphatic and olefinic hydrocarbons in Recent sediments of Greifensee, Switzerland. Geochim. Cosmochim. Acra

44, in press. GRAEF W. and DIEHL H. (1966) The natural normal levels

of carcinogenic PCAH and the reasons therefore. Arch. H!jg. Bakreriol. 150. 49-59.

GRIMMER G. and B~~HNKE H. (1975) Profile analysis of polycychc aromatic hydrocarbons and metal content in sediment layers of a lake. Cancer Left. 1. 75-84.

GRIMMER G.. B~HNKE H. and GLASER A. (1977) Investiga- tion on the carcinogenic burden by air pollution in man. XV. Polycyclic aromatic hydrocarbons in automobile exhaust gas-an inventory. Zenrra/hl. Bukteriol. Parasir-

ertkd. It!fekrionskr. Hyy. .4hr I: Oriy Reikv B. 164,

218-234.

GRUB K. and GROB G. (1972) Techniques of capillary gas chromatography. Possibilities of the full utilization of high-performance columns. Part I : Direct sample injection. C/zromatograp/~ia 5. 3-12.

GROB K. and GROB G. (1976) A new, generally applicable procedure for the preparation of glass capillary columns. J. Chromaroyr. 125. 471-485.

GROB K.. GROB G. and GROB K.. JR (1977) The barium carbonate procedure for the preparation of glass capillary columns; further informations and developments. Chromaroyraphra 10. 181-187.

HANCOCK J. L.. APPLEGATE H. G. and DODD J. D. (1970) Polynuclear aromatic hydrocarbons on leaves. Atmos.

Emwon. 4, 363-370. HASE A. and HIRES R. A. (1976a) On the origin of polycyc-

lit aromatic hydrocarbons in recent sediments: biosynthesis by anaerobic bacteria. Geoc/lim. Cosmochim. Acra 40. 1141-l 143.

HASE A. and HITES R. A. (1976b) On the origin of polycyc- lit aromatic hydrocarbons in the aqueous environment, In lderltifcariorl and Analysis of Organic PoUutanrs irk

Water led. L. H. Keith). pp. 205-214. Ann Arbor. HITES R. A. and BIEMANN W. G. (1975) Identification of

specific organic compounds in a highly anoxic sediment by GC’MS and HRMS. Adc. Chem. Ser. 147, 188-201.

HITES R. A. LAFLAMME R. E. and FARRINGTON J. W. (1977) Sedimentary polycyclic aromatic hydrocarbons: the historical record. Scrence 198, 829-83 I.

KERN W. (1947) tfber das Vorkommen von Chrysen in Erde. Heir. Chim. Acta XXX, 1595-1599.

KNORR M. and SCHENK G. (1968) Synthesis of polycyclic aromatlc compounds by bacteria. Arch. Hyy. Bakteriol. 152. 282-285.

LAFLAMME R. E. and HITES R. A. (1978) The global distribution of polycyclic aromatic hydrocarbons in recent sediments. Geochim. Cosmochim. Acra 42, 289-303.

LAO R. C.. THOMAS R. S.. OJA H. and DUBOIS L. (1973) Application of a gas chromatograph-mass spectrometer- data processor combination to the analysis of polycyclic

aromatic hydrocarbon content of airborne particulates. Anal. Chem. 45, 229-236.

LEE M. L. and HITES R. A. (1976) Characterization of sulfur-containing polycyclic aromatic compounds in carbon blacks. Anal. Chew. 48, 189&l 893.

LEF: M. L.. NOVOTNY M. and BARTL~ K. D. (1976) Gas chromatography ‘mass spectrometric and nuclear mag- netic resonance determination of polynuclear aromatic hydrocarbons in airborne particulates. Anal. C/MI. 48. 1566 1572.

LEL M. L.. PRADO G. P.. HOWARI) J. B. and HITES R. A.

(1977) Source identification of urban airborne polycyclic aromatic hydrocarbons by GC:MS and HRMS. Boomed.

Mass Specrrom 4, I X2- 187.

LUND~ G. and BJORSETH A. (1977) Polycyclic aromatlc hydrocarbons in long-range transported aerosols. Naruw

268. 518-519 MALLET L. and TISSIER M. (1969) Biosynthesis of polycyclic

hydrocarbons of the benzo(a)pyrene type m forest soil. C. R. Sot. Biol. 163, 62-65.

MEHRIYGER P. J. JR.. BLINMA~: E. and PETERSEN K. L. (1977) Pollen influx and volcanic ash. Science 198. 257-261.

MDLLER G.. GRIMMER G. and B~~HNKE H. (1977) Sedimen- tary record of heavy metals and polycyclic aromatic hydrocarbons in Lake Constance. NurUrM’IssPII.~cIIO~(,t1 64. 427-43 I.

National Academy of Sciences (1972). Particulate Pol,v-

cyclic Organic Matter. National Academy of Sciences. NIPKOWF. H. (1927) uber das Verhalten der Skelette plank-

tischer Kieselalgen in geschichtetem Tiefenschlamm des Ziirich-und Baldeggersees. Ph.D. Thesis. ETH Ziirich.

49 PP. SCHELL W. R. (1974) Sedimentation rates and mean resi-

dence times of Pb and Pb-210 in Lake Washington. Puget Sound estuaries. and a coastal.region. Abstracts of Papers submitted for the 37th Annual Meeting American Society of Limnology and Oceanography. Univ. of Washington, Seattle. WA. June 23-28.

STAUB E. (1979) Biologisch-stratigraphische Untersuchun- gen am jungen Sediment des GerwaldstPttersees. Ph.D.

‘Thesis. ETH Ziirich. TISSOT B. P. and WEL~E D. H. (1978) Perroleum Formariorl

and Occurrence. Springer. TSCHOPP J. (1978) Die Verunreinigungen der Seen mit

Schwermetallen; Modelle fiir die Regulierung der Metallkonzentrationen. Ph.D. Thesis. ETH Ziirich.

WAIBEL M. (1976) Air and water contamination by road abrasion. Zenrralbl. Bakreriol. Parnsitenkund. ltfek-

rionstr. Hyg. Abt, I: Orig. Reihe B. 163, 458469. WAKEHAM S. G. (1977) Synchronous fluorescence spec-

troscopy and its application to indigenous and petroleum-derived hydrocarbons in lacustrine sediments. En- viron. Sci. Technol. 11. 272-276.

WAKEHAM S. G. and CARPENTER R. (1976) Aliphatic hydrocarbons in sediments of Lake Washington. Lirnrlol. Oceo- nogr. 21. 71 l-723.

WAKEHAM S. G., SCHAFFNER G. and GIGER W. (1980) Poly- cyclic aromatic hydrocarbons in Recent lake sediments. II. Compounds derived from biogenic precursors during early diagenesis. Geochim. Cosmochim. Acta 44, 415-429.

WEBER H. P. (1979) Sedimentology and Geochemistry of Greifensee, Switzerland. Ph.D. Thesis. ETH Ziirich. In preparation.

WINDWR J. G. JR and H~rrs R. A. (1979) Polycyclic aromatic hydrocarbons in Gulf of Maine sediments and Nova Scotia soils. Geochim. Cosmochim. Acra 43, 27-30.

YO~NGBL~~D W. W. and BLUMER M. (1975). Polycyclic aromatic hydrocarbons in the environment: homologous series in soils and recent marine sediments. Geochml. Cosmochim. Acra 39, 1303-l 3 14.

Documents

Polycyclic aromatic hydrocarbons in Recent lake sediments—I. Compounds having anthropogenic origins